Directory of Researchers

GOMEZ ANDRE Christopher
Graduate School of Maritime Sciences / Department of Maritime Sciences
Professor
Earth Science
Last Updated :2020/08/10

Researcher Profile and Settings

Affiliation

  • <Faculty / Graduate School / Others>

    Graduate School of Maritime Sciences / Department of Maritime Sciences
  • <Related Faculty / Graduate School / Others>

    Faculty of Maritime Sciences / Department of Ocean Safety Systems Sciences

Degree

  • Ph.D.

Teaching

  • Faculty of Maritime Sciences, 2019, Safety Engineering
  • Faculty of Maritime Sciences, 2019, Foundations of Safety Engineering
  • Faculty of Maritime Sciences, 2019, Foundations of Safety Engineering 1
  • Faculty of Maritime Sciences, 2019, Foundations of Safety Engineering 2
  • Faculty of Maritime Sciences, 2019, Risk Management of Maritime Disasters
  • Faculty of Maritime Sciences, 2019, Risk Management of Maritime Disasters 1
  • Faculty of Maritime Sciences, 2019, Risk Management of Maritime Disasters 2
  • Faculty of Maritime Sciences, 2019, Experiments in Marine Science and Technology
  • Faculty of Maritime Sciences, 2019, Experiments in Marine Science and Technology 1
  • Faculty of Maritime Sciences, 2019, Introduction to Marine Science and Technology
  • Faculty of Maritime Sciences, 2019, Introduction to Marine Science and Technology
  • Faculty of Maritime Sciences, 2019, Introduction to Disaster Risk Science 1
  • Faculty of Maritime Sciences, 2019, Introduction to Disaster Risk Science 2
  • Graduate School of Maritime Sciences / Department of Maritime Sciences, 2019, Advanced Ocean Fundamental Science1
  • Graduate School of Maritime Sciences / Department of Maritime Sciences, 2019, Advanced Ocean Fundamental Science2
  • Graduate School of Maritime Sciences / Department of Maritime Sciences, 2019, Climate Change and Natural Hazards in the 21st Century 1
  • Graduate School of Maritime Sciences / Department of Maritime Sciences, 2019, Climate Change and Natural Hazards in the 21st Century 2
  • Graduate School of Maritime Sciences / Department of Maritime Sciences, 2019, Advanced Science and Technology B (Maritime Sciences)

Research Activities

Research Interests

  • Tsunami processes and hazards at the coast (from Newtonian flow to debris-flow)
  • Applied subsurface geophysics (Ground Penetrating Radar and Electric Tomography)
  • Debris flows, lahars and landslides
  • Sediment transfers and related hazards in mountain and volcanic terrains

Published Papers

  • Fine Sedimentation &Infiltration Underneath Debris Flows: Preliminary Results

    Gomez, C.

    May 2020, Sabo Engineering and Scientific Society Proceedings

  • Internal structure of debris flow deposits using UAV photogrammetry and GPR in Kawajiri Town, downstream of Kure City, Hiroshima Prefecture, 2018

    Imai, K., Gomez, C.

    May 2020, Sabo Engineering and Scientific Society Proceedings

  • Characteristics of water and sediment discharge in Tansan-dani gully of Mt. Unzen

    Park, J., Shinohara, Y., Hotta, N., Gomez, C.

    May 2020, Sabo Engineering and Scientific Society Proceedings

  • Ground-Penetrating-Radar Investigation of sedimentation in Sabo dam

    Shimizu, M, Gomez, C.,, Hotta, N.,, Tanaka, N.

    May 2020, Sabo Engineering and Scientific Society Proceedings

  • Analysis of the drifted wood distribution in the aftermath of the 2017 Asakura disaster

    Kanai, S., Shimizu, M., Gomez, C., Uchida, T.

    May 2020, Sabo Engineering and Scientific Society Proceedings, Japanese

  • Toward the Prediction of Sediment Runoff in the Mizunashi River Basin

    Shinohara, Y., Hotta, N., Gomez, C., Tsunetaka, H.

    May 2020, Sabo Engineering and Scientific Society Proceedings, Japanese

  • Unveiling Crucivirus Diversity by Mining Metagenomic Data

    gnacio de la Higuera, George W Kasun, Ellis L Torrance, Alyssa A Pratt, Amberlee Maluenda, Jonathan Colombet, Maxime Bisseux, Viviane Ravet, Anisha Dayaram, Daisy Stainton, Simona Kraberger, Peyman Zawar-Reza, Sharyn Goldstien, James V Briskie, Robyn White, Helen Taylor, Christopher Gomez, David G Ainley, Jon S Harding, Rafaela S Fontenele, Joshua Schreck, Simone G Ribeiro, Stephen A Oswald, Jennifer Arnold, François Enault, Arvind Varsani, Kenneth M Stedman.

    Feb. 2020, Cold Spring Harbor Laboratory Pub. BioRxiv, English

    [Refereed]

  • Coastal Evolution, Geomorphic Processes and Sedimentary Records in the Anthropocene

    Gomez, C., Hart, D., Wassmer, P., Imai, K., Matsui, H.,Shimizu, M.

    Jul. 2019, Forum Geografi, 33, 1 - 24, English

    [Refereed]

    Scientific journal

  • Climate Change and Population Depletion Control over Sediment Hazard and Drifted Wood Hazards in Japan

    Shimizu, M., Gomez, C., Uchida, T.

    May 2019, Sabo Engineering and Scientific Society Proceedings, English

    Symposium

  • Material Fragmentation in the lahar of Unzen Volcano: implications for the transport processes

    Gomez, C., Hotta, N., Shinohara, Y., Tsunetaka, H.

    May 2019, Sabo Engineering and Scientific Society Proceedings, English

    Symposium

  • Earthquake Triggered Multi-Hazard and Risk study Based on Remote Sensing and Geographic Information System

    SAPUTRA A, GOMEZ ANDRE CHRISTOPHER, DEKILOSTIDIS, I, ZAWAR-REZA, P, SRI HADMOKO, D, SARTOHADI J

    Jan. 2019, Geosciences, English

    [Refereed]

    Scientific journal

  • The controls of Mass-movements on drifted wood production and residence during the July 2017 Asakura Disaster, Kyushu, Japan

    GOMEZ ANDRE CHRISTOPHER, Hotta, N., TSUNETAKA H, SHINOHARA Y, UCHIDA T, SHIMIZU M

    Aug. 2018, 16th International Symposium on Geo-disaster Reduction, English

    [Refereed][Invited]

    International conference proceedings

  • In 27 years, lahars have reached some maturity at Mt Unzen Fugendake: geophysical and geomorphometric evidences

    GOMEZ ANDRE CHRISTOPHER, HOTTA, N, TSUNETAKA H, SHINOHARA H, SAKAI Y, KITAMOTO G, SAKAMOTO M

    Aug. 2018, 16th International Symposium on Geo-disaster Reduction, English

    International conference proceedings

  • Geo-physical, -logical, and -morphological investigations of lahars at Semeru Volcano - learning from sediments and multi-imaging

    GOMEZ ANDRE CHRISTOPHER, LAVIGNE F, HADMOKO S.D, WASSMER P, SETIAWAN A, MARDIATNO D, SARTOHADI J

    Aug. 2018, 16th International Symposium on Geo-disaster Reduction Proceedings, English

    [Refereed]

    International conference proceedings

  • Development of a model for estimating the occurrence of debris flows at Mt. Unzen

    SHINOHARA Y, TSUNETAKA H, GOMEZ ANDRE CHRISTOPHER, KITAMOTO G, HOTTA N, SAKAI Y, SAKAMOTO M

    Aug. 2018, 16th International Symposium on Geo-disaster Reduction ICGDR, English

    [Refereed]

    International conference proceedings

  • Deciphering flooding characteristics for three predecessors of the 2011 Tohoku-Oki tsunami at Sendai, Japan

    WASSMER P, GOMEZ ANDRE CHRISTOPHER, HART D.E, HIRAISHI T, AZUMA R, KOENIG B, TRAUTMANN M

    Aug. 2018, 16th International Symposium on Geo-disaster Reduction, English

    International conference proceedings

  • Post-eruptive lahars at Kali Putih following the 2010 eruption of Merapi Volcano, Indonesia: occurrences and impacts

    HADMOKO D.S, BELIZAL E, LAVIGNE F, ARIS MARFAI, GOMEZ ANDRE CHRISTOPHER, BACHTIAR W.M, GILANG A.D, SARTOHADI J, SURATMAN W, STARHEIM C

    Jun. 2018, Journal of Natural Hazards, English

    [Refereed]

    Scientific journal

  • Earthquake and stormwater lifelines: a method for revealing multi-hazard interactions to improve Engineering Resilience

    HART D, GOMEZ ANDRE CHRISTOPHER, GIOVINAZZI S, DAVIES C

    Jun. 2018, ECEE Publications, English

    [Refereed]

    International conference proceedings

  • 雲仙普賢岳ガリーにおける崖錐発達の実態と土石流発生条件との関係

    北本 楽, 経隆 悠, 篠原 慶規, 堀田 紀文, GOMEZ ANDRE CHRISTOPHER, 酒井 佑一, 矢野 敦久

    May 2018, 平成30年度日本砂防学会 Proceedings, Japanese

    Research society

  • “GOTONG ROYONG” : APLIKASI SELULER INTERAKTIF DALAM MANAJEMEN TANGGAP DARURAT

    SETIAWAN M.A, BANGSA J.P, KRISTIANA N.P, ISMAIL M, Muhammad R.A, PRASTIKA K.P, MARDIATNO D, SUSMAYADI M, WINARYO, NGADISIH, GOMEZ ANDRE CHRISTOPHER

    May 2018, Proceedings of: PERTEMUAN ILMIAH TAHUNAN- RISET KEBENCANAAN

    [Refereed]

    Scientific journal

  • Understanding the Variations of Internal Sedimentary Structures and Material Characteristics at Unzen using Ground Penetrating Radar

    GOMEZ ANDRE CHRISTOPHER, HOTTA N, SHINOHARA Y, SAKAI Y, TSUNETAKA H, YANO A, SAKAMOTO M

    May 2018, 平成30年度日本砂防学会 Proceedings, 2p., English

    Research society

  • Shallow Landslides & Drifted Wood Hazards following the July 2017 Rainfall Event in Asakura, Kyushu

    GOMEZ ANDRE CHRISTOPHER, HOTTA N, SHINOHARA Y, TSUNETAKA H, LISSAK C, SHIMIZU M

    May 2018, The 5th International Symposium on Mega Earthquake Induced Geo-disasters and Long Term Effects, English

    International conference proceedings

  • Point-cloud Technology and 2D Computational Flow Dynamic Modelling for Rapid Hazards and Disaster Risk Appraisal on Yellow-Creek Fan, Southern Alps of New Zealand

    GOMEZ ANDRE CHRISTOPHER, PURDIE H

    May 2018, Progress in Earth and Planetary Science, English

    [Refereed][Invited]

    Scientific journal

  • Gotong Royong Aplokasi Selular Interaktif

    GOMEZ ANDRE CHRISTOPHER

    May 2018, Permetuan Ilmiah Tahunan Ke-5 riset Kebenchanaan 2018 Ikatan Ahli Kebencanaan Indonesia, ISBN 978-602-5539-28-2, 664 - 670

    [Refereed]

    International conference proceedings

  • Glacier Recession Uncorks Sediment Transfer at Fox Glacier (NZ)

    GOMEZ ANDRE CHRISTOPHER, PURDIE H

    May 2018, Proceedings of The 5th International Symposium on Mega Earthquake Induced Geo-disasters and Long Term Effects, 2p., English

    International conference proceedings

  • Dome Evolution at Unzen Volcano between 2003 and 2015: Erosion and Destabilization

    GOMEZ ANDRE CHRISTOPHER, HOTTA N, SHINOHARA Y

    May 2018, Proceedings of The 5th International Symposium on Mega Earthquake Induced Geo-disasters and Long Term Effects, 2p., English

    International conference proceedings

  • Determining earthquake susceptible areas Southeast of Yogyakarta, Indonesia – Outcrop analysis from Structure from Motion (SfM) and Geographic Information System (GIS)

    SAPUTRA A, GOMEZ ANDRE CHRISTOPHER, DELIKOSTIDIS I, ZAWAR-REZA P, SRI HADMOKO D, SARTOHADI J, SETIAWAN A.M

    Apr. 2018, Geosciences, English

    [Refereed]

    Scientific journal

  • GOMEZ ANDRE CHRISTOPHER

    Feb. 2018, Journal of Volcanology and Geothermal Research, English

    [Refereed]

    Scientific journal

  • GOMEZ ANDRE CHRISTOPHER, LAVIGNE F, SRI HADMOKO D, WASSMER P

    Jan. 2018, Journal of Volcanology and Geothermal Research, English

    [Refereed]

    Scientific journal

  • GOMEZ ANDRE CHRISTOPHER, KENNEDY B

    Dec. 2017, Journal of Volcanology and Geothermal Research, English

    [Refereed]

    Scientific journal

  • Tsunami Flood Simulation Investigation using NAYS-2D code in Kobe-City

    GOMEZ C

    Jun. 2017, HAL Scientific Open Archives, hal-01531850, English

    Scientific journal

  • Claire Kain, Patrick Wassmer, James Goff, Catherine Chague-Goff, Christopher Gomez, Deidre Hart, Daniela Fierro, Geraldine Jacobsen, Atun Zawadzki

    In the absence of eyewitness reports or clear sedimentary structures, it can be difficult to interpret tsunami deposits or reconstruct tsunami inundation patterns. The emplacement dynamics of two historical tsunami deposits were investigated at seven transects in Okains Bay, New Zealand, using a combined geospatial, geomagnetic and sedimentological approach. The tsunami deposits are present as layers of sand and silt intercalated between soils and become finer and thinner with distance inland. The deposits are attributed to the 1960 and possibly the 1868 tsunamis, based on radiometric dating and correlation with historical records. Measurements of Magnetic Fabric (MF: Anisotropy of Magnetic Susceptibility) and particle size were used to reconstruct the evolution of flow dynamics laterally and vertically. A combination of statistical methods, including spatial autocorrelation testing, Spearman's rank order correlation, Principal Component Analysis (PCA) and K-means cluster analysis, was applied to examine relationships between MF parameters and sediment texture, and infer depositional hydrodynamics. Flow patterns deduced from MF show the estuary channel acted as a conduit for inundation, with flow commonly aligned sub-perpendicular to the estuary bed. MF and sediment data suggest deposition occurred from settling during laminar flow. Evidence of both uprush and backwash deposition, as well as wave reflection from infrastructure, was found. Statistical analysis of data showed significant relationships between grain size parameters and MF parameters associated with flow speed and magnetic fabric type. PCA and cluster analysis differentiated samples into two primary hydrodynamic groups: (1) samples deposited from laminar flow; and (2) samples deposited close to the limit of inundation, which includes samples deposited further inland, those affected by flow convergence, and those in the upper part of tsunami deposits. This approach has potential as a tool for reconstructing hydrodynamic conditions for palaeotsunamis and by combining spatial and statistical analyses, large-scale investigations can be more easily performed. Copyright (c) 2016 John Wiley & Sons, Ltd.

    WILEY, Apr. 2017, EARTH SURFACE PROCESSES AND LANDFORMS, 42 (5), 763 - 780, English

    [Refereed]

    Scientific journal

  • SfM-MVS Haar Wavelet Decomposition as a tool to examine mixed grain-size sedimentary Outcrop

    GOMEZ C

    Feb. 2017, HAL Scientific Open Archives, English

    Scientific journal

  • Ground Penetrating Radar Analysis of Slope and Lake Sediments Interplay: A Survey of Lake Pearson

    GOMEZ C, Miller J

    Feb. 2017, HAL Scientific Open Archives, Hal-01524351, English

    [Refereed][Invited]

    Scientific journal

  • Aditya Saputra, Trias Rahardianto, Christopher Gomez

    Adequate knowledge of geological structure is an essential for most studies in geoscience, mineral exploration, geo-hazard and disaster management. The geological map is still one the datasets the most commonly used to obtain information about the geological structure such as fault, joint, fold, and unconformities, however in rural areas such as Central Java data is still sparse. Recent progress in data acquisition technologies and computing have increased the interest in how to capture the high-resolution geological data effectively and for a relatively low cost. Some methods such as Airborne Laser Scanning (ALS), Terrestrial Laser Scanning (TLS), and Unmanned Aerial Vehicles (UAVs) have been widely used to obtain this information, however, these methods need a significant investment in hardware, software, and time. Resolving some of those issues, the photogrammetric method structure from motion (SfM) is an image-based method, which can provide solutions equivalent to laser technologies for a relatively low-cost with minimal time, specialization and financial investment. Using SfM photogrammetry, it is possible to generate high resolution 3D images rock surfaces and outcrops, in order to improve the geological understanding of Indonesia. In the present contribution, it is shown that the information about fault and joint can be obtained at high-resolution and in a shorter time than with the conventional grid mapping and remotely sensed topographic surveying. The SfM method produces a point-cloud through image matching and computing. This task can be run with open-source or commercial image processing and 3D reconstruction software. As the point cloud has 3D information as well as RGB values, it allows for further analysis such as DEM extraction and image orthorectification processes. The present paper describes some examples of SfM to identify the fault in the outcrops and also highlight the future possibilities in terms of earthquake hazard assessment, based on fieldwork in the South of Yogyakarta City.

    AMER INST PHYSICS, 2017, PROCEEDING OF THE 6TH INTERNATIONAL SYMPOSIUM ON EARTH HAZARD AND DISASTER MITIGATION (ISEDM) 2016, 1857, English

    [Refereed]

    International conference proceedings

  • Trias Rahardianto, Aditya Saputra, Christopher Gomez

    Research on landslide susceptibility has evolved rapidly over the few last decades thanks to the availability of large databases. Landslide research used to be focused on discreet events but the usage of large inventory dataset has become a central pillar of landslide susceptibility, hazard, and risk assessment. Indeed, extracting meaningful information from the large database is now at the forth of geoscientific research, following the big-data research trend. Indeed, the more comprehensive information of the past landslide available in a particular area is, the better the produced map will be, in order to support the effective decision making, planning, and engineering practice. The landslide inventory data which is freely accessible online gives an opportunity for many researchers and decision makers to prevent casualties and economic loss caused by future landslides. This data is advantageous especially for areas with poor landslide historical data. Since the construction criteria of landslide inventory map and its quality evaluation remain poorly defined, the assessment of open source landslide inventory map reliability is required. The present contribution aims to assess the reliability of open-source landslide inventory data based on the particular topographical setting of the observed area in Niigata prefecture, Japan. Geographic Information System (GIS) platform and statistical approach are applied to analyze the data. Frequency ratio method is utilized to model and assess the landslide map. The outcomes of the generated model showed unsatisfactory results with AUC value of 0.603 indicate the low prediction accuracy and unreliability of the model.

    AMER INST PHYSICS, 2017, PROCEEDING OF THE 6TH INTERNATIONAL SYMPOSIUM ON EARTH HAZARD AND DISASTER MITIGATION (ISEDM) 2016, 1857, English

    [Refereed]

    International conference proceedings

  • Fault Detection in the Curah Lengkong at Mt Semeru, Indonesia - Topographic and Ground Penetrating Radar Evidences -

    GOMEZ C, LAVIGNE F, SRI HADMOKO D

    2017, Institute of Electronics, Information and Communication Engineers Technical Report, English

    [Refereed][Invited]

    International conference proceedings

  • Aditya Saputra, Trias Rahardianto, Christopher Gomez

    Adequate knowledge of geological structure is an essential for most studies in geoscience, mineral exploration, geo-hazard and disaster management. The geological map is still one the datasets the most commonly used to obtain information about the geological structure such as fault, joint, fold, and unconformities, however in rural areas such as Central Java data is still sparse. Recent progress in data acquisition technologies and computing have increased the interest in how to capture the high-resolution geological data effectively and for a relatively low cost. Some methods such as Airborne Laser Scanning (ALS), Terrestrial Laser Scanning (TLS), and Unmanned Aerial Vehicles (UAVs) have been widely used to obtain this information, however, these methods need a significant investment in hardware, software, and time. Resolving some of those issues, the photogrammetric method structure from motion (SfM) is an image-based method, which can provide solutions equivalent to laser technologies for a relatively low-cost with minimal time, specialization and financial investment. Using SfM photogrammetry, it is possible to generate high resolution 3D images rock surfaces and outcrops, in order to improve the geological understanding of Indonesia. In the present contribution, it is shown that the information about fault and joint can be obtained at high-resolution and in a shorter time than with the conventional grid mapping and remotely sensed topographic surveying. The SfM method produces a point-cloud through image matching and computing. This task can be run with open-source or commercial image processing and 3D reconstruction software. As the point cloud has 3D information as well as RGB values, it allows for further analysis such as DEM extraction and image orthorectification processes. The present paper describes some examples of SfM to identify the fault in the outcrops and also highlight the future possibilities in terms of earthquake hazard assessment, based on fieldwork in the South of Yogyakarta City.

    AMER INST PHYSICS, 2017, PROCEEDING OF THE 6TH INTERNATIONAL SYMPOSIUM ON EARTH HAZARD AND DISASTER MITIGATION (ISEDM) 2016, 1857 (030001), doi: 10.1063/1.4987060, English

    [Refereed]

    International conference proceedings

  • Spatio-Temporal Distribution of Landslides in Java and the Triggering Factors

    HADMOKO SRI D, LAVIGNE F, SARTOHADI J, GOMEZ C, DARYONO D

    2017, Forum Geografi, English

    [Refereed]

    Scientific journal

  • Seismic vulnerability assessment of residential buildings using logistic regression and geographic information system (GIS) in Pleret Sub District (Yogyakarta, Indonesia)

    SAPUTRA A, RARADIANTO T, REVINDO M.D, DELIKOSTIDIS I, HADMOKO D.S, SARTOHADI J, GOMEZ C

    2017, Geoenvironmental Disasters, English

    [Refereed]

    Scientific journal

  • Azusa Yamashita, Christopher Gomez, Kelly Dombroski

    The Great East-Japan Disaster, which began with the earthquake and tsunami of March 2011, prompted discussions throughout the Japanese lesbian, gay, bisexual and transgender (LGBT) community on the vulnerabilities that LGBT people face during disaster because of sexual orientation, gender identity and gender expression. This short essay shares some of the post-disaster experiences, challenges and discussions of the LGBT community in Japan. Reports coming out of the LGBT community have stressed that pre-disaster discrimination and fears of discrimination and repression among LGBT people have hampered their recovery. There is a real fear of being discriminated against and having their family and friends discriminated against. This situation has led to the isolation and vulnerability of LGBT individuals. Despite the majority being reluctant to come out publically, the disaster forced numerous individuals to reveal their gender identity, particularly when confronted with life in shelters, the lack of supply of medication and so on. In turn, this has resulted in instances of discrimination and bullying. These accounts reveal that the main aims of disaster policies and disaster ethics - based on addressing the greatest good of the majority - largely fail to cater for LGBT people, who are not only victims of the disaster but can also be valuable contributors in the Disaster Risk Reduction (DRR) process.

    ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD, Jan. 2017, GENDER PLACE AND CULTURE, 24 (1), 64 - 71, English

    [Refereed][Invited]

    Scientific journal

  • Berton Panjaitan, Christopher Gomez, Eric Pawson

    In 2010 a tsunamigenic earthquake triggered tsunami waves reaching the Mentawai archipelago in less than ten minutes. Similar events can occur any time as seismic scholars predict enormous energy remains trapped on the Sunda Megathrust - approximately 30 km offshore from the archipelago. Therefore, the local community of Mentawai is vulnerable to tsunami hazards. In the absence of modern technology to monitor the sea surface interventions, existing strategies need to be improved. This study was based on a qualitative research and literature review about developing coping capacity on tsunami hazards for Mentawai. A community early-warning system is the main strategy to develop the coping capacity at the community level. This consists of risk knowledge, monitoring, warning dissemination, and capability response. These are interlocked and are an end-to-end effort. From the study, the availability of risk assessments and risk mappings were mostly not found at dusun, whereas they are effective to increase tsunami risk knowledge. Also, the monitoring of tsunami waves can be maximized by strengthening and expanding the community systems for the people to avoid the waves. Moreover, the traditional tools are potential to deliver warnings. Lastly, although the local government has provided a few public facilities to increase the response capability, the people often ignore them. Therefore, their traditional values should be revitalized.

    AMER INST PHYSICS, 2017, PROCEEDING OF THE 6TH INTERNATIONAL SYMPOSIUM ON EARTH HAZARD AND DISASTER MITIGATION (ISEDM) 2016, 1857 (100002), doi: 10.1063/1.4987108, English

    [Refereed]

    International conference proceedings

  • Photogrammetry-based Texture Analysis of a Volcaniclastic Outcrop-peel: Low-cost Alternative to TLS and Automation Potentialities using Haar Wavelet and Spatial-Analysis Algorithms

    GOMEZ C, KATAOKA K, SAPUTRA A, WASSMER P, URABE A, MORGENROTH J, KATO A

    2017, Forum Geografi, English

    [Refereed]

    Scientific journal

  • Eroded Coastal Dune and Deposits in North Sumatra (Indonesia) following the 2004 Boxing Day Tsunami - A Geophysical Approach -

    GOMEZ C, LAVIGNE F, WASSMER P

    2017, Institute of Electronics, Information and Communication Engineers Technical Report, English

    [Refereed][Invited]

    International conference proceedings

  • Heather Purdie, Paul Bealing, Emily Tidey, Christopher Gomez, Justin Harrison

    Processes that drive iceberg calving at the margins of freshwater terminating glaciers are still poorly understood. This knowledge-gap is in part due to the challenge of obtaining good in situ data in a highly dynamic and dangerous environment. We are using emerging remote technologies, in the form of a remote controlled jet boat to survey bathymetry, and Structure from Motion (SfM) to characterize terminus morphology, to better understand relationships between lake growth and terminus evolution. Comparison of results between the jet boat mounted dual-frequency Garmin fish-finder with an Odom Echotrac DF3200 MKII with 200/38 kHz dual-frequency transducer, showed that after a sound velocity adjustment, the remote survey obtained depth data within +/- 1 m of the higher grade survey equipment Water depths of up to 240 m were recorded only 100 m away from the terminus, and subaerial cliff height ranged from around 6 to 33 m, with the central region of the terminus more likely to experience buoyancy. Subaqueous ice ramps are ephemeral features, and in 2015 multiple ice ramps extended out into the lake from the terminus by 100-200 m. The consistent location of some of the subaqueous ramps between surveys may indicate that other processes, for example, subglacial hydrology, also influence evolving terminus morphology. (C) 2016 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Dec. 2016, GLOBAL AND PLANETARY CHANGE, 147, 1 - 11, English

    [Refereed]

    Scientific journal

  • Daniel M. Blake, Thomas M. Wilson, Christopher Gomez

    Coverage of road markings by volcanic ash is one of the most commonly reported impacts to surface transportation networks during volcanic ashfall. Even minimal accumulation can obscure markings, leading to driver disorientation, diminished flow capacity and an increase in accidents. Such impacts may recur due to repeated direct ashfall (i.e. during prolonged eruptions) and/or due to the re-suspension of ash by wind, water, traffic or other human activities, and subsequent secondary deposition on the road surface. Cleaning is thus required to restore and maintain road network functionality. Previous studies have not constrained ash accumulation measurements to inform road cleaning initiation or plans for safe road operations in environments containing ash. This study uses a laboratory approach with digital image analysis to quantify the percentage of white road marking coverage by three types of volcanic ash with coarse, medium and fine particle size distributions. We find that very small accumulations of ash are responsible for road marking coverage and suggest that around 8 % visible white paint or less would result in the road markings being hidden. Road markings are more easily covered by fine-grained ash, with ash area densities of similar to 30 g m(-2) (estimated at <0.1 mm surface thickness) potentially causing markings to be obscured. For the coarse ash in our study, road marking coverage occurs at area densities of similar to 1000-2200 g m(-2) (similar to 1.0-2.5 mm depth) with ash colour and line paint characteristics causing some of the variation. We suggest that risk management measures such as vehicle speed reduction and the initiation of road cleaning activities should be taken at or before the lower thresholds as our experiments are conducted at a relatively short horizontal distance and the ability to observe road markings when driving will be comparatively reduced.

    SPRINGER, Oct. 2016, ENVIRONMENTAL EARTH SCIENCES, 75 (20), English

    [Refereed]

    Scientific journal

  • C. Gomez, T. Oguchi, I. S. Evans

    01 May 2016, Geomorphology, 260, 1 - 3

    [Refereed]

    Scientific journal

  • F. C. Persendt, C. Gomez

    Accurate delineation of drainage networks (DNs) is crucial for hydrological or hydraulic modelling, and the comprehension of fluvial processes. This task presents challenging aspects in complex lowland terrains with subtle relief and particularly for data poor-areas like the Cuvelai river basin (CRB), Namibia, where the present study takes place. In the CRB standard methods of drainage network extraction from low resolution gridded digital elevation models (DEMs) are unsuitable, hence airborne Light Detection and Ranging (LiDAR) solutions have been utilized. However, LiDAR also presents challenges to large areal applications, especially with a surface roughness exceeding the capacity of numerous algorithms. Indeed, LiDAR-based DEMs (2 and 50 m resolutions) need to be hydrologically corrected and smoothed to enable the extraction of scale-relevant geomorphologic features such as DNs. In the present contribution, channels from topographic maps (blue lines) were compared to those from hydrologically corrected and uncorrected LiDAR DEMs, heads-up digitized channels from high resolution digital aerial orthophotographs, field-mapped channels and auxiliary data. The 'maximum gradient deterministic eight (D8)' GIS algorithm was applied to the corrected and uncorrected LiDAR DEMs using two network extraction methods: area threshold support and curvature/drop analysis. Different progressive flow accumulation threshold values (12) were used to delineate channels with these methods. Validation was performed between the field-mapped channels, the modelled channels and those derived from multiple sources. Additionally, spatial and quantitative analyses were performed on geomorphologic parameters and indices. The results have shown that hydrologically corrected LiDAR DEMs offer useful details for identifying low order stream segments in headwaters, while blue lines derived from the national hydrography datasets for watersheds, located in elevated and low-lying areas of the study area, underestimated total stream lengths for field-mapped channels by 153% and 88.5%, respectively. This study also confirmed that DNs can be extracted from complex low-terrain areas with standard GIS algorithms and accurate field data. The results will aid national mapping agencies in data-poor regions to modernize their national hydrography datasets and to account for changing land surface conditions that can affect channel spatial arrangements over time. (C) 2015 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, May 2016, GEOMORPHOLOGY, 260, 32 - 50, English

    [Refereed]

    Scientific journal

  • GOMEZ C, PURDIE H

    2016, Geoenvironmental Disaster, 3 (23), English

    [Refereed]

    Scientific journal

  • Spatial Analysis in Geomorphology(2): How Spatial Analysis and Large Dataset Have Reshaped Surface Processes and Landform Research

    GOMEZ C, OGUCHI T, EVANS I.S

    2016, Geomorphology, (260), 1 - 6, English

    [Refereed][Invited]

    Scientific journal

  • Geospatial Assessment of Coseismic Landslides in Baturagung Area

    SAPUTRA A, HADMOKO D.S, SARTOHADI J, GOMEZ C

    2016, Forum Geografi, (29), 99 - 113, English

    [Refereed]

    Scientific journal

  • SAPUTRA A, GOMEZ C, HADMOKO S.D, SARTOHADI J

    2016, Geoenvironmental Disaster, English

    [Refereed]

    Scientific journal

  • Changes on a Seismically Active Urban Coast: Observations from Laboratory Christchurch.

    HART D, BYUN D.-S, GIOVINAZZI S, HUGHES M, GOMEZ C

    Sep. 2015, Australasian Coasts and Ports Conference Conference Paper, English

    [Refereed][Invited]

    International conference proceedings

  • 小花和宏之, 早川裕弌, 加藤顕, GOMEZ Christopher

    日本地形学連合, Apr. 2015, 地形, 36 (2), 87 - 106, Japanese

    [Refereed]

  • Surveying technique for terrain analysis using small unmanned aircraft and autonomous GNSS equipped and digital camera

    OBANAWA H, HAYAKAWA Y, KATO A, GOMEZ C

    2015, 地形, Japanese

    [Refereed]

    Scientific journal

  • C. Gomez, T. Oguchi, I. S. Evans

    ELSEVIER SCIENCE BV, Aug. 2015, GEOMORPHOLOGY, 242, 1 - 2, English

    [Refereed][Invited]

    Scientific journal

  • PERSENDT F, GOMEZ C, ZAWAR-REZA P

    2015, JAMBA, 7 (1), English

    [Refereed]

    Scientific journal

  • C. Lissak, O. Maquaire, J. -P. Malet, F. Lavigne, C. Virmoux, C. Gomez, R. Davidson

    The objective of this paper is to demonstrate the applicability of ground-penetrating radar (GPR) for monitoring the displacement of slow-moving landslides. GPR data are used to estimate the vertical movement of rotational slides in combination with other surveying techniques. The study area is located along the Normandy coast (northeast France) where several rotational landslides are continuously affected by a seasonal kinematic regime (low displacement rates of 0.01 to 0.10 m yr(-1)) and periodically by major acceleration events (high displacement rates of 1.0 to 7.0 m per event).

    COPERNICUS GESELLSCHAFT MBH, 2015, NATURAL HAZARDS AND EARTH SYSTEM SCIENCES, 15 (6), 1399 - 1406, English

    [Refereed]

    Scientific journal

  • Heather Purdie, Christopher Gomez, Stephen Espiner

    Rapid recession and thinning of mountain glaciers worldwide are resulting in changes to glacier surface morphology, which are exacerbated by increased rockfall and debris accumulation at lateral margins. Rockfall can be a hazard to people visiting and working on glaciers. Relationships between rockfall and the changing glacier surface were explored at Fox Glacier, where tourism is a key industry. Using a simple rockfall model, it was found that rocks could travel a further 50 m out onto the glacier in 2012 compared with 2008. An improved understanding of natural hazards is essential to the sustainability of the industry, given the importance of glacier-related tourism in the local and regional economies.

    WILEY-BLACKWELL, Dec. 2015, NEW ZEALAND GEOGRAPHER, 71 (3), 189 - 202, English

    [Refereed]

    Scientific journal

  • Christopher Gomez, Patrick Wassmer

    The Unzen Volcano, located at the centre of the Shimabara Peninsula is a stratovolcano that has left scars both in the landscapes and the lives of local inhabitants. After almost two centuries of slumber, the Unzen erupted during the period 1990-1995, producing numerous dome-collapses pyroclastic flows that engulfed a large part of the structure. Using a dataset retrieved by structure-from-motion from historical imagery, the present contribution provides an insight on the landscape trajectory of the volcano between the period 1947 and 2013, using the lenses of geomorphology and biogeography. The results have shown that the volcano has been evolving in two different manners since the eruption. The summit area of the volcano still holds a large amount of material (pyroclasts of 50 m depth have been measured from the 1998 imagery). This area has seen a return of the vegetation, which contrasts with the foot of the volcano, trapped in a concrete coffin, limiting the return of vegetation and living the wounds of the eruption open. Finally, at the exit of the Mizunashigawa, the impacts of the eruption have spread to the shore, with a linear expansion over the sea of almost 500 m. In Conclusion, this contribution shows that it isn't much the volcanic eruption that modified the landscape over long periods of time, but the human infrastructure that stops some part of the landscape to evolve.

    GROUPE FRANCIAS GEOMORPHOLOGIE, Jul. 2015, GEOMORPHOLOGIE-RELIEF PROCESSUS ENVIRONNEMENT, 21 (3), 205 - 216, English

    [Refereed]

    Scientific journal

  • Anisha Dayaram, Sharyn Goldstien, Gerardo R. Argueello-Astorga, Peyman Zawar-Reza, Christopher Gomez, Jon S. Harding, Arvind Varsani

    Our understanding of the diversity and abundance of circular replication associated protein (Rep) encoding single stranded (CRESS) DNA viruses has increased considerably over the last few years due to a combination of modern sequencing technologies and new molecular tools. Studies have used these to identify and recover CRESS DNA viruses from a range of different marine organisms, including copepods, shrimp and molluscs. In our study we identified 79 novel CRESS DNA viruses from three mollusc species (Austrovenus stutchburyi, Paphies subtriangulata and Amphibola crenata) and benthic sediments from the Avon-Heathcote estuary in Christchurch, New Zealand. The genomes recovered have varying genome architectures, with all encoding at least two major ORFs that have either unidirectional or bidirectional organisation. Analysis of the Reps of the viral genomes showed they are all highly diverse, with only one Rep sequence sharing 65% amino acid identity with the Rep of gastropod-associated circular DNA virus (GaCSV). Our study adds significantly to the wealth of CRESS DNA viruses recovered from freshwater and marine environments and extends our knowledge of the distribution of these viruses. (C) 2015 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Apr. 2015, INFECTION GENETICS AND EVOLUTION, 31 (31), 284 - 295, English

    [Refereed]

    Scientific journal

  • WASSMER P, GOMEZ C, ISKANDASIAH T.Y.W.M, LAVIGNE F, SARTOHADI J

    2015, Frontiers in Earth Science: Geomagnetism and Paleomagnetism, English

    [Refereed]

    Scientific journal

  • Christopher Gomez, Yuichi Hayakawa, Hiroyuki Obanawa

    SfM-MVS (Structure from Motion and Multiple-View Stereophotogrammetry) is part of a series of technological progresses brought to the field of earth-sciences during the last decade or so, which has allowed geoscientists to collect unprecedented precise and extensive DSMs (Digital Surface Model) for virtually no cost, rivaling LiDAR (Light Detection and Ranging) technology. Previous work on SfM-MVS in geosciences has been solely exploring data acquired for the purpose of SfM-MVS, but no research has been done in the exploration of photographic archives for geomorphological purposes. Therefore, the present publications aims to present the usage of SEM-MVS applied to historical aerial photographs in Japan, in order to (1) demonstrate the potentials to extract topographical and vegetation data and (2) to present the potential for chronological analysis of landscape evolution. SfM-MVS was implemented on black-and-white and colour aerial photographs of 1966, 1976, 1996, 2006 and 2013, using the commercial software Photoscanpro (R). Firstly, the photographs were masked, tied to GPS points; secondly the positions of the cameras and the 3D pointcloud were calculated; and thirdly the 3D surface was created. Data were then exported in the GIS software ArcGIS for analysis. Results also proved satisfactory for the reconstruction of 3D past-geomorphological landscapes in coastal areas, riverine areas, and in hilly and volcanic areas. They also prove that the height of trees and large vegetation features can also be calculated from aerial photographs alone. Diachronic analysis of the evolution in 3D landforms presented more difficulties, because the resolution of the early photographs was lower than the recent ones. Volume and surface calculations should therefore be conducted carefully. Although the method holds merit and great promise in the exploration of active landscapes that have widely changed during the 20th century; the authors have also reflected on the issues linked to large datasets, mostly because the processing of these large datasets is still in need of improvement. Moreover there is no proof that an ever increasing resolution brings any major advance to the geomorphological paradigms. (C) 2015 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Aug. 2015, GEOMORPHOLOGY, 242, 11 - 20, English

    [Refereed][Invited]

    Scientific journal

  • Claire L. Kain, Christopher Gomez, Deirdre E. Hart, Catherine Chague-Goff, James Goff

    Tsunamis transport large amounts of sediment and can leave recognisable signatures in the landscape. The form and composition of onshore tsunami deposits are a function of wave dynamics, sediment availability and characteristics of the local environment, the latter of which also partially controls preservation of the deposit. This research reviews these relationships in a global context and assesses the connection between tsunami deposit particle size and four controlling parameters: climate (temperature and rainfall), density of tsunami sediments, degree of coastal protection and distance between tsunami source and sediment deposition. An international dataset of tsunami deposit locations and texture was compiled from published literature and existing databases. Values for environmental variables were calculated for each location from global datasets of temperature, rainfall, coastline shape and tsunami source locations. Spearman's rank-order correlation, Principal Component Analysis (PCA) and hierarchical Cluster Analysis (CA) were used to analyse relationships between these variables. PCA results show an inverse relationship between particle size and sediment density, climate variables and distance from source. CA results support this, suggesting a cluster structure controlled primarily by particle size and secondly by climate and sediment density, These relationships can be explained by the influence of the environment on antecedent morphology and the composition of sediments available for tsunami transport. (C) 2015 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Oct. 2015, MARINE GEOLOGY, 368, 1 - 14, English

    [Refereed]

    Scientific journal

  • Jordan Miller, Justin Morgenroth, Christopher Gomez

    Accurate tree measurement is necessary for applications such as resource appraisal, and biophysical and ecological modelling. This research tests the potential to use a low-cost hand-held camera alongside structure-from-motion with multi-view stereo-photogrammetry (SfM-MVS) to accurately measure trees. SfM-MVS is a computer vision technique, in which the geographic coordinates of objects are calculated from a series of photographs, resulting in a 3D point cloud model. This research tested the ability of SfM-MVS to reconstruct spatially accurate 3D models from which 2D (height, crown spread, crown depth, stem diameter) and 3D (volume) tree metrics could be estimated. Thirty small, potted trees were photographed and measured with traditional dendrometry to evaluate SfM-MVS derived tree size estimates. Tree volume was obtained via the water displacement approach xylometry. SfM-MVS estimates of 2D tree metrics had errors (RMSE - root mean squared error) as low as 3.74% (RMSEtree (height) = 3.74%, RMSEcrown depth = 11.93%, RMSEcrown (spread) = 14.76%, RMSEDBH = 9.6%). SfM-MVS estimates of 3D tree metrics were better for the main stem than for the slender branches (RMSEStem = 12.33%, RMSEBranches = 47.53%, RMSETotal Volume = 18.53%). Apart from height and crown depth, all modelled variables had negative bias, suggesting that SfM-MVS tends to underestimate the size of trees. The results show that SfM-MVS is capable of producing estimates of 2D and 3D metrics with accuracy comparable to that of laser scanning (i.e. LiDAR). Factors like the position of the tree relative to its surroundings, the background scene and the ambient lighting, appear to affect model success. SfM-MVS provides a low-cost alternative to remote sensing technologies currently used such as terrestrial laser scanning and, as no specialised equipment is required, it is able to be used by people with little expertise or training. Future research is required for exploring the suitability of SfM-MVS for specific applications requiring accurate dendrometry. (C) 2015 Elsevier GmbH. All rights reserved.

    ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2015, URBAN FORESTRY & URBAN GREENING, 14 (4), 932 - 940, English

    [Refereed]

    Scientific journal

  • Claire Kain, Christopher Gomez, Patrick Wassmer, Franck Lavigne, Deirdre Hart

    The 2004 tsunami transformed the coast of Indonesia. This research investigates a sand dune area in Lampuuk, Sumatra, that was scoured by tsunami flow. We assessed geomorphology one-year post-event and examine the timescale of vegetation recovery. Ground Penetrating Radar (GPR) evidence shows an eroded succession of thin dipping units, overlain by aeolian layers 0 to 50cm thick. Incipient dunes were absent, indicating limited dune rebuilding at one-year post-tsunami, possibly resulting from channelised airflow and the absence of vegetation. Recolonisation by vegetation was initially limited but progressed rapidly between 2005 and 2011, highlighting the temporal non-linearity of recovery processes.

    WILEY-BLACKWELL, Dec. 2014, NEW ZEALAND GEOGRAPHER, 70 (3), 165 - 178, English

    [Refereed]

    Scientific journal

  • Brendan Duffy, Jocelyn Campbell, Michael Finnemore, Christopher Gomez

    The Springfield thrust fault at Dalethorpe, west Canterbury, New Zealand, provides a test case to explore the correlation between shear wave velocities at a range of scales, and direct field observations of distributed deformation and outcrop properties. The Springfield fault ruptures to the surface through hard Torlesse greywacke, overlain on a flight of late Quaternary glacio-fluvial terraces by similar to 5 m of gravel. Fault slip has displaced all but the lowest terraces, revealing the geometry and location of faulting. We used multi-channel analysis of surface waves and meter-scale cross-hole measurements to map shear wave velocities below the lowest, apparently undisplaced, terrace. We correlated these surveys with geotechnical parameters measured at outcrops and investigated relationships in the laboratory. Both field and laboratory results indicate that the shear wave velocity of Torlesse greywacke declines sharply with increasing fracture density. Field surveys further indicate that relatively unweathered, high velocity greywacke is being exhumed in a bivergent wedge between two opposite-facing thrusts. The fracturing and low shear wave velocities are focused in a wide, low-velocity damage zone that has developed in the hanging wall of the main thrust, and a smaller but similar feature in the hanging wall of the backthrust This is consistent with the geomorphology of the site. Our correlations of geomorphic indicators of deformation with fault zone velocity structure provide a useful method with which to characterize the distribution of cumulative strain. This type of analysis has utility for land use planning on, or close to, active faults, especially where they are obscured by fluvial deposits. (C) 2014 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Dec. 2014, ENGINEERING GEOLOGY, 183, 216 - 229, English

    [Refereed]

    Scientific journal

  • Christopher Gomez

    This article presents the cartoons and comic strips that the author draws and has used in his teaching of physical geography at the undergraduate level since 2011. In the context of an image-based culture, this article discusses the pedagogic goals that cartoons and comic strips fulfil: enhancing learning and creativity, associating pleasure with learning, pushing students to think 'outside the box' and relating the students' learning experience to a media framework popular with students. Cartoons and comic strips also answer particular necessities related to the teaching of physical geography. Using characters placed in hypothetical situations, they explain the process of doing geography and being a physical geographer.

    WILEY-BLACKWELL, Aug. 2014, NEW ZEALAND GEOGRAPHER, 70 (2), 140 - 145, English

    [Refereed]

    Scientific journal

  • Christopher Gomez

    The Sakurajima Volcano is one of the most active volcanoes in the world with regular activity dominated by vulcanian eruptions since 1955. Located in Kagoshima Prefecture - Kyushu Island, Japan - the Sakurajima Volcano is a stratovolcano with two main vents at the summit, the Kitadake and the Minamidake, and a third smaller central vent, the Nakadake. The two firsts peak at 1117 and 1060 m dominate the slopes mainly composed of lava-flow deposits, secondary volcaniclastic material and recent ejectas from the Vulcanian eruptions. Although the volcano has been very closely monitored by Japanese Universities (mostly Kyoto University and Kagoshima University) and governmental agencies, there has been very little geomorphological investigation of the structure of the volcano. Using the digital photogammetric method SfM-MVS (Structure from Motion and Multiple-view Stereophotogrammetry) applied to historical aerial photographs, the present contribution aims to provide an analysis of the volcanic structure and the recent bio-geomorphological evolution for the period 1947-2006. First, the results have proved that SfM-MVS is a method that can be successfully applied to aerial photographs for diachronic reconstruction of geomorphological landscape evolution. This method is especially important in active volcanic areas, as the geomorphology can change very rapidly within the historical period. Secondly, the results have shown that during the last similar to 60 years, the summit area of the Sakurajima has greatly evolved: the morpholology of the Minamidake crater has changed due to its regular explosive activity; the upper slopes have been covered in ejecta, modifying their elevation and their smoothness. The lower slopes have seen the apparition of lahar deposition areas, while valleys, upslope, have widened due to the lahar activity and the upward progression of the deposits. The 3D derived from SfM-MVS has also shown how the lahar deposits are using the topographic low, created on top of the lava deposits and in between lava deposit to accumulate mid-slopes, rather than accumulating on the lower volcanic apron. This is accentuated by the construction of SABO dams that keep a large amount of the material on the slopes. Finally, as this publication has been carried out using the freely available imagery from the GSI (Geospatial Information Authority of Japan) at 200 dpi, higher resolution imagery can even open further possibilities for the monitoring of volcano evolution in Japan and in countries providing long series of historical imagery. (C) 2014 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Jun. 2014, JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 280, 1 - 13, English

    [Refereed]

    Scientific journal

  • Claire L. Kain, Christopher Gomez, Deirdre E. Hart, Patrick Wassmer, James Goff, Colette Starheim

    A set of anomalous sand deposits enclosed between paleosol layers were identified in Okains Bay on eastern Banks Peninsula, New Zealand. These were investigated to determine flow patterns during their deposition and the influence of topography on these patterns. This was achieved using a combination of sedimentary analyses, Magnetic Fabric (MF) and Ground Penetrating Radar (GPR). Two washover facies were identified, based on stratigraphic context, particle size analyses and flow direction during deposition from MF results. These deposits, which decrease in thickness with distance inland, comprise two layers of fine-medium sand and are situated 1.3 km from the coast on an estuary margin. Results show the sand sheets were deposited as overwash from the estuary, with the extent and deposition patterns controlled by local topography and the presence of relict dune ridges. MF is demonstrated as a versatile and important technique for determining flow patterns and depositional mechanisms. Flow patterns identified here from MF highlight the importance of river channels as conduits for short-lived high energy marine inundation events. Additionally, these results support the importance of topography in controlling deposition patterns, which has important implications for the reconstruction of events where the paleotopography is unknown. (C) 2014 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Apr. 2014, MARINE GEOLOGY, 350, 16 - 26, English

    [Refereed]

    Scientific journal

  • Modeling of Inaccessible Areas using UAV-based Aerial Photography and Structure from Motion

    OBANAWA H, HAYAKAWA Y, GOMEZ C

    2014, Transaction of the Japanese Geomorphological Union, 35 (3), 283 - 294, Japanese

    [Refereed]

    Scientific journal

  • Christopher Gomez, Akira Kato

    Point-clouds acquired using remote sensing, such as lasers or photogrammetric techniques, have grown exponentially in the last decade, providing data containing hundreds of millions of points with a density reaching hundreds of thousand points per square centimetre - when working on relatively small areas. This progress has been developed concomitantly with an increasing democratization of UAVs, in such a way that even in hardly accessible areas UAV-based photogrammetric techniques have provided researchers with detailed point-clouds. Provided those dataset, the paradigms have therefore shifted from data collection difficulties, to data processing limitations and usage. The present contribution therefore aims to provide an example of data processing using a voxel-based approach of gravel surfaces in order to derive more than the traditional surface roughness. The algorithm decomposes the surface into voxels and sub-voxels in order to determine if there are surfaces overlapping each other, showing the presence of cavities. Such dataset will then provide the necessary dataset to create metrics to improve the modelling of boundary layers dynamics in computational fluid dynamics for instance.

    IEEE, 2014, 2014 IEEE INTERNATIONAL CONFERENCE ON AEROSPACE ELECTRONICS AND REMOTE SENSING TECHNOLOGY (ICARES), 205 - 209, English

    [Refereed]

    International conference proceedings

  • OBANAWA H, HAYAKAWA Y, SAITO H, GOMEZ C

    2014, Journal of the Japanese Society of Photogrammetry and Remote Sensing, 53 (2), 67 - 74, Japanese

    [Refereed]

    Scientific journal

  • The February 21st, 2005 catastrophic waste-avalanche at Leuwigajah dumpsite, Bandung, Indonesia.

    LAVIGNE F, WASSMER P, SURONO, HADMOKO D.S, ISKANDARSYAH Y, GAILLARD J.C, FORT M, TEXIER P, BOUN HENG M, DAVIES T, GOMEZ C

    2014, Geoenvironmental Disaster, (1), 1 - 10, English

    [Refereed]

    Scientific journal

  • Automatic Detection of Damage Zones in Port-au-Prince: the Object-Oriented Approach, an Operational Complement to Visual Interpretation

    THI TANH H.P, APPARICIO P, WEBER C, MATHON D, GOMEZ C

    2014, Journal of Disaster Management, (23), 53 - 66, English

    [Refereed]

    Scientific journal

  • J. Morgenroth, C. Gomez

    Efforts to improve the efficiency and efficacy of tree structure and crown architecture measurement are necessary to reduce error associated with indirect estimation of volume, which affects biophysical and ecosystem modelling, as well as resource assessment. In this short communication, we test the potential for a commercial SfM-MVS (Structure from Motion coupled with Multiple-View Stereophotogrammetry) software package, Photoscan-Professional, to accurately determine tree height, stem diameter, and eventually volume. SfM is a technique in computer vision, which calculates the 3D position of objects in a scene from a series of photographs. It uses a technique assuming that an object in a 3D scene is located on a vector between the image of the object in the camera and the object itself. The technique allows the construction of a 3D pointcloud, such as the one produced by laser technologies - terrestrial or airborne LiDAR. SfM requires no camera calibration or control points to construct an initial model. Moreover, it is a low-cost alternative to laser technologies. The second part of our method - MVS - is a visualization technique that reconstructs a 3D textured mesh of the scene from the SfM-derived pointcloud and RGB photographs. As a proof of concept, our methods were limited to two scenarios: (1) a single potted tree in a lab environment, where exact measurements could be made, and (2) two trees of different species and size in natural environments to test feasibility outside the laboratory. Precise measurements of tree height and stem diameter were compared with estimates obtained from the 3D model created using SfM-MVS. The results indicate that the SfM method is a promising - and inexpensive - alternative to terrestrial LiDAR and 3D scanners. Tree height estimates had error of 2.59%, while stem diameter estimates had error of 3.7%. The MVS algorithm used in this study was developed for plan surfaces such as topography or 'compact' objects and does not provide a representative 3D mesh for slender trees, although it works well for large stems. The authors link this disparity to the complex branching structure of trees. Future work requires (1) the development of effective automated volume reconstruction software specific to trees, and (2) the validation of the wide-scale applicability of the technology, which must include trees of various size, species, and growth forms. Moreover, future testing must include more complex environments, such as heterogeneous urban sites or closed-canopy forest sites where the proximity of other features may limit the utility of the new technology. (C) 2013 Elsevier GmbH. All rights reserved.

    ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2014, URBAN FORESTRY & URBAN GREENING, 13 (1), 198 - 203, English

    [Refereed]

    Scientific journal

  • Anisha Dayaram, Sharyn Goldstien, Peyman Zawar-Reza, Christopher Gomez, Jon S. Harding, Arvind Varsani

    Over the past couple of years highly diverse novel ssDNA viruses have been discovered. Here, we present the first ssDNA virus, Gastropod-associated circular ssDNA virus (GaCSV), recovered from a mollusc Amphibole crenate Martyn 1784, which is a deposit feeder that grazes microorganisms and organic detritus on the surface of tidal mudflats. The GaCSV (2351 nt) genome contains two large bidirectionally transcribed ORFs. The smaller ORF (874 nt) has similarities to viral replication-associated protein (Rep) sequences of some bacteria and circoviruses, whereas the larger ORF (955 nt) does not relate to any sequences in public databases and we presume it potentially encodes the capsid protein. Phylogenetic analysis shows that the GaCSV Rep clusters with Rep-like sequences of bacterial origin, highlighting the role of ssDNA viruses in horizontal gene transfer. The occurrence of previously unknown viruses in organisms associated with human pollution is a relatively unexplored field.

    SOC GENERAL MICROBIOLOGY, May 2013, JOURNAL OF GENERAL VIROLOGY, 94 (5), 1104 - 1110, English

    [Refereed]

    Scientific journal

  • Colette C. A. Starheim, Christopher Gomez, Justin Harrison, Claire Kain, Nicholas J. Brewer, Kirsty Owen, Danang Sri Hadmoko, Heather Purdie, Peyman Zawar-Reza, Ian Owens, Patrick Wassmer, Franck Lavigne

    Previous research on debris-flow deposit structure typically reports little to no visually discernible stratigraphy. The preliminary findings presented here provide evidence for more complex internal deposit architecture with inverse grading and subunits thought to reflect individual flow surges. Ground-penetrating radar surveys, geospatial data and field observations are used to describe 10 subunits traceable over the 14 lateral radargrams imaging the lower 38 m of the deposit. Additional subunits are depicted further upslope in a longitudinal transect. As well as demonstrating the need for continued investigation of deposit architecture using non-traditional techniques, these results may help improve future interpretations of post-event deposits.

    WILEY-BLACKWELL, Apr. 2013, NEW ZEALAND GEOGRAPHER, 69 (1), 26 - 38, English

    [Refereed]

    Scientific journal

  • Field Tree Measurement using Terrestrial Laser for Radar Remote Sensing

    Akira Kato, Manabu Watanabe, Justin Morgenroth, Christopher Gomez

    2013, Proceedings of APSAR2013, TU2.R3.4, English

    International conference proceedings

  • Recent behavior and sustainable future management of the Waiho River, Westland, New Zealand.

    T. DAVIES, B. CAMPBELL, B. HALL, C. GOMEZ

    2013, New Zealand Journal of Hydrology, (52), 41 - 56, English

    [Refereed]

    Scientific journal

  • Colette C. A. Starheim, Christopher Gomez, Tim Davies, Franck Lavigne, Patrick Wassmer

    The hazardous and unpredictable nature of lahars makes them challenging to study, yet the in-flow processes characterizing these events are important to understand. As a result, much of the previous research on lahar sedimentation and flow processes has been derived from experimental flows or stratigraphic surveys of post-event deposits. By comparison, little is known on the time-dependent sediment and flow dynamics of lahars in natural environments. Using video-footage of seven lahars on the flanks of Semeru Volcano (East Java, Indonesia), the present study offers new insights on the in-flow evolution of sediment in natural lahars. Video analysis revealed several distinctive patterns of sediment entrainment and deposition that varied with time-related fluctuations in flow. These patterns were used to generate a conceptual framework describing possible processes of formation for subsurface architectural features identified in an earlier lateral survey of lahar deposits on Semeru Volcano (Gomez and Lavigne, 2010a). The formation of lateral discontinuities was related to the partial erosion of transitional bank deposits followed by fresh deposition along the erosional contact. This pattern was observed over the course of several lahar events and within individual flows. Observations similarly offer potential explanations for the formation of lenticular features. Depending on flow characteristics, these features appeared to form by preferential erosion or deposition around large stationary blocks, and by deposition along channel banks during episodes of channel migration or channel constriction. Finally, conditions conducive to the deposition of fine laminated beds were observed during periods of attenuating and surging flow. These results emphasize the difficulties associated with identifying process-structure relationships solely from post-event deposit interpretation and illustrate that an improved understanding of the time-dependent sediment dynamics in lahars may be advantageous when interpreting post-event structural features. (C) 2013 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Apr. 2013, JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 256, 96 - 104, English

    [Refereed]

    Scientific journal

  • A. DAYARAM, S. GOLDSTIEN, P. ZAWAR-REZA, C. GOMEZ, J. HARDING, A. VARSANI

    2013, American Society for Microbiology Journal – Genome Announvements, 1 (3), English

    [Refereed]

    Scientific journal

  • P. WASSMER, J.-P. SCHWARTZ, C. GOMEZ, P. BARRERE

    2013, Geografica Fysica e dynamic quaternaria, 36 (1), 199 - 210, English

    [Refereed]

    Scientific journal

  • Martin Schuster, Christopher Gomez

    This paper describes the development and implementation of a location based service for tsunami evacuation routes. Based on the position of the mobile phone the system provides a real-time calculation for an escape route out of the hazard zone. A smartphone application visualizes the route on a map. Nowadays, tsunami hazard zones are well known and determined with complex simulation models. Evacuation routes in such hazard zones are mostly sign posted along roads and visualized in evacuation plans. People who are inside a tsunami hazard zone have to make themselves familiar with the evacuation plans and have to find their own way out of the zone. The developed concept shows the possibility of a location based service to determine an escape route and visualize the result on a map. In addition, the route is the shortest possible way out of the zone. The concept is implemented for a test area in Christchurch, New Zealand. The developed prototype consists of a three tier architecture. The mobile Android application (client) determines the position of the smartphone and is responsible for the visualization of the result. A calculation program on the server side calculates the shortest route out of the hazard zone. The necessary data for this calculation come from a spatial data base which is the third component in this architecture. The whole system allows the user to calculate an escape route out of the hazard zone at the touch of a button. Implemented in an existing tsunami warning application it would be a life-saving service.

    AUSTRIAN ACAD SCIENCE PRESS, 2013, GI_FORUM 2013: CREATING THE GISOCIETY, 206 - 215, English

    [Refereed]

    International conference proceedings

  • C. GOMEZ, D. HART

    2013, Geographical Journal, 179 (3), 272 - 277, English

    [Refereed]

    Scientific journal

  • Christopher Gomez

    With the increasing availability of data, geo-sciences have experienced deep changes in handling and processing it. One of the presently explored research directions concerns the systematic decomposition and understanding of topographical features, without the subjective interactions of humans. This can eventually lead to fully automated algorithms for topographic analysis and understanding. This paper aims at being a contribution to this broad research area for the specific cases of stratovolcanoes, whose general geometry are very similar to a perfect cone. More specifically, this paper addresses two issues: (1) is it possible to separate erosion features (local variations) from structural features (large variations) on stratovolcanoes, through mathematical expression; (2) can information on volcanic activity-intensity, age, etc.-be retrieved from a topographic analysis? The study has been conducted from two volcanoes in Central Java (Indonesia): the Merapi and the Merbabu. The DEM of these volcanoes has been sampled using concentric circles with a radius ranging from 500 to 5,000 m (horizontal distance) to the summit. The data conversion and sampling was performed in ArcMap(A (R)), while the data analysis was carried out with Matlab(A (R)), using Discrete Meyer wavelet decomposition. Results provide an insight on large-scale topographic variations (long-wave wavelet) that have been separated from rapidly varying topographic features such as lahar channels (short-wave wavelets). Observations proved that flanks where the most recent volcanic activity occur-like at Merapi Volcano on the S-SE flank-present a very low variability of long-wave variations, whereas short-wave variations are important. The author argues that this feature is due to highly erosive lahars that dig the valleys combined with a recent production of material and volcanic growth keeping the overall structure regular. Flanks with lesser activity are characterized at the two volcanoes by important long-wave variations-most certainly due to long-term differential erosion-and different level of short-waves variations. Comparing the two volcanoes, results show that the valleys of Merapi and Merbabu volcanoes are deeply incised, indicating recent periods of high activity, with reworkable material eroded by lahars and other channels deepening processes. The topography of the summit area of Merapi Volcano is smoother than at Merbabu Volcano, where deep erosion features extend up to the summit area. This difference is most certainly due by the material production at the summit of Merapi Volcano. Developing such classification is important for automated mapping and computer recognition of volcanic past activities and their impacts on landscapes. It is the based for the development of decision trees that assist computer assisted and automated computer vision.

    SPRINGER, Nov. 2012, ENVIRONMENTAL EARTH SCIENCES, 67 (5), 1423 - 1430, English

    [Refereed]

    Scientific journal

  • GOMEZ Christopher

    Nov. 2012, Environ Earth Sci, 67 (5), 1423 - 1430, English

    [Refereed]

    Scientific journal

  • Christopher Gomez, Iman Soltanzadeh

    Although volcanic eruptions are well-known to be the trigger of some weather and climatic changes, land-cover changes by pyroclastic-flows and lahars do not get this recognition, neither do major hazards such as tsunami. These two earth processes are even lesser considered as being able to modify other earth processes they are not directly connected to, such as landslides or river discharge in non-connected basins more than a hundred kilometres away. In this contribution the authors argue that these ideas are mainly driven by the process of being educated in a single academic discipline and once put to the test interactions and retroactions between earth processes and atmospheric processes are far more reaching than commonly thought. For this study, the site of Java Island (Indonesia) was chosen to conduct (1) an analysis of a major tsunami impact in the same area as the 2006 Java tsunami and (2) an analysis of the post-eruption impacts of Merapi Volcano after a major eruption excluding any ejecta in the atmosphere for the sake of the demonstration. The atmospheric feedback simulations were conducted using the regional climate model (RegCM-4) with calibration from weather stations in Java Island. As a result, both simulations have proven that large scale deposits of pyroclasts (not introducing the ejectas sent in the atmosphere) and tsunamis can have outstanding impacts on the atmospheric situation and the bio-geomorphologic evolution of the landscape in the following weeks to months. Interestingly enough these impacts are not limited to the area impacted by the earth process and the effect are not linear in time as they work following thresholds. These rainfalls tele-impacts are important enough to, in turn, modify earth-surface processes in areas remote from the original phenomenon. This system acts in the same manner as a famous butterfly in Africa that could trigger a hurricane on the other side of the Atlantic Ocean. Copyright (C) 2012 John Wiley & Sons, Ltd.

    WILEY-BLACKWELL, Jun. 2012, EARTH SURFACE PROCESSES AND LANDFORMS, 37 (7), 790 - 796, English

    [Refereed]

    Scientific journal

  • Christopher Gomez, Kyoko S. Kataoka, Kenji Tanaka

    The Towada Caldera Volcano is located between the prefectures of Aomori and Akita - Northeast Honshu Island, Japan. The caldera, today filled by a lake, has produced 15,000 years ago a complex eruption emplacing an ignimbrite topped by the lake outburst flood deposit, through which the present Oirase River erodes. This flood deposit has shaped the geomorphologic feature named Sanbongi Fan, on which Towada City extends. This flood event hypothesis is mainly based on sedimentological and geomorphological evidences of floods mainly from outcrops retrieved from the Sanbongi Fan area. Because of the lack of extended outcrops - typical of the Japanese environment - the present paper has therefore put the theory to the test using GPR (Ground Penetrating Radar) radargram extending along a 640 m length. The GPR used for the survey was a Pulse-ekko-Pro with 50 MHz antennas, and the software Reflex was used to process the data. The radargrams have displayed a sole unit, which the GPR could not penetrate. It can be interpreted as the ignimbrite. On top of this deposit a series of subhorizontal layers, with the alternation between a backset and a foreset extends between 5 m and 3 m depth. Above 3 m, the units are regular and subhorizontal. The deposit is also characterized by the extensive presence of boulders, which are located along three bands: (1) on top of the ignimbrite; (2) in the units deposited by the outburst flood, between 3 and 5 m depths; (3) and in the units close to the surface, although part of these punctual elements are most certainly anthropogenic. Compared with the outcrops, the present research confirms that the material located above the ignimbrite material have been deposited by the outburst flood, creating large-sheet patterns, which have transported boulders. These sheets display backset and foreset patterns, depending on the position of the deposit, indicating flow pulsation or surges under a 'high-energy-flow' condition. (C) 2012 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Jun. 2012, JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 229, 44 - 49, English

    [Refereed]

    Scientific journal

  • Tohoku Tsunami: Understanding the Human Elements of a Coastal Disaster

    GOMEZ C, HART D, WASSMER P

    2012, Coastal News, 49, 3 - 5, English

    [Refereed]

    Scientific journal

  • Development of the AMS method for unconsolidated sediments. Application to tsunami deposits

    Patrick Wassmer, Christopher Gomez

    AMS (Anisotropy of Magnetic Susceptibility) is a geophysical method, which uses the electromagnetic properties of samples as a proxy of their fabric. Commonly used on hard rocks and cohesive sediments, the method has never been developed for unconsolidated sediments before. In this contribution, we present the usability of the AMS method on unconsolidated rocks and the new insights that AMS brings for the study of tsunami deposits, and for geomorphology. We have been working on the deposits of the coast of North Sumatra (Indonesia) because a devastating tsunami has struck these coasts and has redesigned the coastal environment and sediments distribution the 26 December 2004. Hence, this geographical setting has provided us with the necessary material for the study. We have carried Out the analysis from 6 samples, which evidenced: (i) a first layer deposited by an uprush oriented to the SSW; (ii) a decanting phase; (iii) a layer deposited by a backwash oriented to the North; (iv) two other uprushes that deposited two units oriented to the SSW and the SSE. This research has proven that the AMS could be used on unconsolidated deposits, and that the orientation and an approximation of the energy during deposition could be inferred as well. It leads to new developments in marine and or fluvial geomorphology, even for unconsolidated sediments.

    GROUPE FRANCIAS GEOMORPHOLOGIE, Jul. 2011, GEOMORPHOLOGIE-RELIEF PROCESSUS ENVIRONNEMENT, 3 (3), 279 - 290, English

    [Refereed]

    Scientific journal

  • N. A. K. Nandasena, Raphael Paris, Norio Tanaka

    Coastal boulders are good evidence of high-energy events, but the distinction between storm and tsunami boulders remains difficult to identify and mathematical models are still in their preliminary stages. In a pioneering contribution, Nott (1997, 2003) developed hydrodynamic equations to assess the minimum wave height required to initiate transport of a coastal boulder by tsunamis or storm surges. These equations are widely cited and used, but they can be improved. In this study, Nott's equations have been revised: (1) the equation for the submerged boulder scenario has been revised by rearranging the lift area of the lift force, (2) the subaerial boulder scenario has been reconsidered by rearranging lift area and omitting inappropriate use of inertia force, and (3) the joint bounded scenario was revised by balancing force components in the lifting direction, and the effect of slope at the pre-transport location is tested. Calculations are performed for four case studies: boulders in Western and Eastern Australia (data after Nott, 1997, 2003), boulders in southeastern Italy (data after Scicchitano et al., 2007), storm boulders in Iceland (data after Etienne and Paris, 2010), and 2004 tsunami boulders in Sumatra (data after Paris et al., 2009). The minimum flow velocity required to initiate the transport of submerged boulders in the revised equation is less than that in Nott's equation (e.g., reductions up to 56% for submerged boulders and 65% for joint bounded blocks). The minimum flow velocity required to initiate the transport of subaerial boulders from the revised equation also differed in comparison with Nott's equation (e.g., 4-22% for boulders detached from a seawall by the 2004 tsunami in Sumatra), while Nott's equation was not applicable to some boulders (e.g., beach rock boulders transported from the nearshore by the 2004 tsunami). If we consider a joint bounded scenario for storm boulders in Iceland, the minimum flow velocity differs -43 to +41% from the results from Non's equation. A boulder transport histogram is then introduced to represent the range of flow velocity that satisfies the requirements for initial transport of a boulder in different modes: sliding, rolling, and saltation. The boulder transport histogram can be used to predict the possible initial transport mode of a boulder from the flow velocity. These theoretical results are compared to field data, thus suggesting the initial transport mode of boulders and their pre-transport locations. The boulder transport histogram would be a valuable tool to reconstruct the magnitude of prehistoric high energy events such as tsunamis or storm surges in terms of flow velocity. (C) 2011 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Mar. 2011, MARINE GEOLOGY, 281 (1-4), 70 - 84, English

    [Refereed]

    Scientific journal

  • The Atmospheric Impacts of Large Tsunamis – Case Study in Java, Indonesia

    GOMEZ C, SOLTANZADEH, I, HART D.E

    2011, Coastal News, 48, 5 - 7, English

    Scientific journal

  • A new technique for examining palaeotsunamis arrives on New Zealand shores: the Anisotropy of Magnetic Susceptibility.

    GOMEZ C, HART D

    2011, Coastal News, 47, 7 - 8, English

    Scientific journal

  • C. Gomez, M. Janin, F. Lavigne, R. Gertisser, S. Charbonnier, P. Lahitte, S. R. Hadmoko, M. Fort, P. Wassmer, V. Degroot, H. Murwanto

    Borobudur basin is located in Central Java (Indonesia), 30 km to the North of Yogyakarta City. The basin is famous for its UNESCO world heritage temple and for one of the world's most active volcanoes, Merapi, located to the East of Borobudur basin. Merapi is one of the three andesitic volcanoes that surround the basin: Merapi, Merbabu and Sumbing volcanoes. Therefore, volcanic activity has strongly influenced the evolution of Borobudur basin. The object of this contribution is to present the evolution of Borobudur basin over the last 161,000 years in the light of volcanic influence. The methodology and tools developed for this research span over different areas of expertise, from geochemistry, geology and geomorphology to remote sensing. GIS and archeology. Results highlight the following points: 1. Two major volcanic events deposited volcaniclastic materials up to tens of meters thick similar to 119,000 years BP and similar to 31,000 years BP. in the Southern part of the Borobudur basin. The second volcanic event could correspond to the collapse of the older Ancient Merapi (Camus et al., 2000) or Proto-Merapi Stage (Newhall et al., 2000). 2. There is no trace in the Borobudur basin of a large debris avalanche <31,000 BP, indicating that the young debris avalanche inferred in the literature for Merapi Volcano was either too small to reach 20 km from the actual summit of Merapi; or, despite the orientation of the avalanche caldera rim on Merapi Volcano, the debris avalanche was deposited more towards the South, completely eroded or covered by younger deposits. 3. There are several generations of paleolakes in the Borobudur basin. The latest one has shrunk until historical times, corroborating the theory of Newhall et al. (2000) and Murwanto et al. (2004) that Borobudur Temple was standing by a water body. Most of these paleolakes were impounded following volcanic events. Paleolakes most probably originated from the blockage of the hydrographic network by volcanic material. 4. Borobudur temple was never buried under volcanic material during historic times. (C) 2010 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Oct. 2010, JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 196 (3-4), 245 - 264, English

    [Refereed]

    Scientific journal

  • C. Gomez, F. Lavigne

    Semeru Volcano is the highest mountain of Java (Indonesia), and a vulcanian explosion occurs every 15 minutes on average, since 1967. Thus a constantly renewed stock of material and the heavy monsoon rainfall [3700 mm yr(-1) at 1500 m above sea level (a.s.l.)] provide a perfect setting for the study of lahars and their deposits. Hence, we examined the architecture of lahars' terraces 9.5 km from the summit in the Curah Lengkong Valley. We first used ground penetrating radar (GPR) over vertical exposures of the lahars cut-bank terraces. This allowed us to better understand transversal radargrams across terraces, which are not visually accessible in the field. Preliminary results from a single radargram are very instructive, since (1) they prove that the lateral architecture does not correspond to that observed from banks only; (2) we could observe the presence of lenses and stratigraphic discontinuities; (3) the setting of the various units can also help reconstruct deposition processes and the chronology of different units. In order to finalize these preliminary results, we however need to perform multiple GPR radargrams and provide a complete set of results. Copyright (C) 2010 John Wiley & Sons,

    JOHN WILEY & SONS LTD, Jul. 2010, EARTH SURFACE PROCESSES AND LANDFORMS, 35 (9), 1116 - 1121, English

    [Refereed]

    Scientific journal

  • C. Gomez, F. Lavigne

    Lahars present a particular problem for automated block detection using machine vision, because their patterns and apparent sizes and shapes vary with the flow. To address this difficulty, we developed a simple algorithm to detect blocks in lahars at Semeru Volcano based on traditional RGB (Red Green Blue) 25 frame-per-second videos. The detection algorithm is based on the combination of two methods: (1) a determination of blocks by color segregation, and (2) objects movements' detection. After image processing. we converted the data into a signal that emphasizes the presence of large blocks. Results compare very well with video-images, since 100% of peaks of amplitude >300 corresponded to large blocks traveling down the channel. This method ultimately aims at contributing to lahars automatic detection systems, where little funding is available, since it only requires a traditional camera and a computer. (C) 2009 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Feb. 2010, JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 190 (3-4), 379 - 384, English

    [Refereed]

    Scientific journal

  • WASSMER P, SCHNEIDER J.-L, FONFREGE A.-V, LAVIGNE F, PARIS R, GOMEZ C

    2010, Marine Geology, 275 (1-4), 255 - 272, English

    [Refereed]

    Scientific journal

  • Raphael Paris, Patrick Wassmer, Junun Sartohadi, Franck Lavigne, Benjamin Barthomeuf, Emilie Desgages, Delphine Grancher, Philippe Baumert, Franck Vautier, Daniel Brunstein, Christopher Gomez

    Large tsunamis are major geomorphic crises, since they imply extensive erosion, sediment transport and deposition in a few minutes and over hundreds of kilometres of coast. Nevertheless, little is known about their geomorphologic imprints. The December 26. 2004 tsunami in Sumatra (Indonesia) was one of the largest and deadliest tsunamis in recorded human history. We present a description of the coastal erosion and boulder deposition induced by the 2004 tsunami in the Lhok Nga Bay, located to the West of Banda Aceh (northwest Sumatra). The geomorphological impact of the tsunami is evidenced by: beach erosion (some beaches have almost disappeared); destruction of sand barriers protecting the lagoons or at river mouths; numerous erosion escarpments typically in the order of 0.5-1.5 m when capped by soil and more than 2 ill in duties; bank erosion in the river beds (the retreat along the main river is in the order of 5-15 m, with local retreats exceeding 30 m); large scars typically 20-50 cm deep on slopes; dislodgement of blocks along fractures and Structural ramps on cliffs. The upper limit of erosion appears as a continuous trimline at 2030 In a.s.l., locally reaching 50 m. The erosional imprints of the tsunami extend to 500 m from the shoreline and exceed 2 km along riverbeds. The overall coastal retreat from Lampuuk to Leupung was 60 in (550,000 m(2)) and locally exceeded 150 m. Over 276,000 m(3) of coastal sediments were eroded by the tsunami along the 9.2 km of sandy coast. The mean erosion rate of the beaches was similar to 30 m(3)/m of coast and locally exceeded 80 m(3/)m. The most eroded coasts were tangent to the tsunami wave train, which was coming from the southwest. The fringing reefs were not efficient in reducing the erosional impact of the tsunami. The 220 boulders measured range from 0.3 to 7.2 m large (typically 0.7-1.5 m), with weights from over 50 kg up to 85 t. We found one boulder, less than 1 m large, at 1 km from the coastline, but all the others were transported less than 450 m (<7 m a.s.l.). No lining landward boulder size distribution could be detected. The coincidence of different size modes, from boulders to fine sands. with independent spatial distributions. suggests that all the material was not transported in suspension, but rather by a combination of suspension and bed load transport. Finally, the spatial and size distributions of tsunami boulder deposits mostly depend on the location and characteristics of their source (coral reef, beach rock, platform, darns), together with clast and Surface interference during transport. One year after, the coastal environment in northwest Sumatra is still in a post-tsunami dynamic. Thus, the difference between the largest tsunamis (height>30 m) and the moderate tsunamis (height<10 m) could be their long-term impact on coastal environments. (C) 2008 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Mar. 2009, GEOMORPHOLOGY, 104 (1-2), 59 - 72, English

    [Refereed]

    Scientific journal

  • Franck Lavigne, Raphael Paris, Delphine Grancher, Patrick Wassmer, Daniel Brunstein, Franck Vautier, Frederic Leone, Francois Flohic, Benjamin De Coster, Taufik Gunawan, Christopher Gomez, Anggri Setiawan, Rino Cahyadi, Fachrizal

    This paper presents the results from an extensive field data collection effort following the December 26, 2004 earthquake and tsunami in Banda Aceh, Sumatra. The data were collected under the auspices of TSUNARISQUE, a joint French-Indonesian program dedicated to tsunami research and hazard mitigation, which has been active since before the 2004 event. In total, data from three months of field investigations are presented, which detail important aspects of the tsunami inundation dynamics in Banda Aceh. These include measurements of runup, tsunami wave heights, flow depths, flow directions, event chronology and building damage patterns. The result is a series of detailed inundation maps of the northern and western coasts of Sumatra including Banda Aceh and Lhok Nga. Among the more important findings, we obtained consistent accounts that approximately ten separate waves affected the region after the earthquake; this indicates a high-frequency component of the tsunami wave energy in the extreme near-field. The largest tsunami wave heights were on the order of 35 m with a maximum runup height of 51 m. This value is the highest runup value measured in human history for a seismically generated tsunami. In addition, our field investigations show a significant discontinuity in the tsunami wave heights and flow depths along a line approximately 3 km inland, which the authors interpret to be the location of the collapse of the main tsunami bore caused by sudden energy dissipation. The propagating bore looked like a breaking wave from the landward side although it has distinct characteristics. Patterns of building damage are related to the location of the propagating bore with overall less damage to buildings beyond the line where the bore collapsed. This data set was built to be of use to the tsunami community for the purposes of calibrating and improving existing tsunami inundation models, especially in the analysis of extreme near-field events.

    BIRKHAUSER VERLAG AG, Feb. 2009, PURE AND APPLIED GEOPHYSICS, 166 (1-2), 259 - 281, English

    [Refereed][Invited]

    Scientific journal

  • C. Gomez, F. Lavigne, D. S. Hadmoko, N. Lespinasse, P. Wassmer

    In 2006, a series of block-and-ash flows swept the southwestern and southern flanks of Merapi Volcano, Java, Indonesia. In the K. Gendol valley, near the village of Kaliadem, we conducted a GPR survey on the most distal lobe of the June 14th second block-and-ash flow deposit. For this 100 m-long transect, we used a commercial GPR RAMAC (c) mounted with 100 MHz antennas. We measured the topography with a synchronized GPS and a laser rangefinder. Back at the laboratory, we processed the dataset with the software REFLEX (R) Data of the subsurface reveals a series of layers, separated by strong reflective horizons. These horizons are the manifestation of intercalations of fine materials in between more coarse layers. The architecture of these layers presents progradation, retrogradation and aggradation patterns that we relate to the block-and-ash flow deposition process. Based on these observations we proposed a relative chronology of the deposition and a simple conceptual model of the deposition. The model show that the block-and-ash flow can deposit either long, close to horizontal single layers, or shorter layers that imbricate themselves, following different patterns (progradation, retrogradation or aggradation). Nevertheless we remained cautious, since we only studied a very short portion of the deposit, and similar experiences need to be repeated. Moreover there are reflections in the radargram that we could not identify, and further studies need to be conducted. (C) 2009 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Sep. 2009, GEOMORPHOLOGY, 110 (3-4), 118 - 127, English

    [Refereed]

    Scientific journal

  • C. Gomez, F. Lavigne, N. Lespinasse, D. S. Hadmoko, P. Wassmer

    In 2006 Merapi volcano, Indonesia, erupted for a few months, producing several block-and-ash flows reaching a maximum distance of 7.5 km from the main vent. During the eruption, we conducted a survey on those flow deposits in the Gendol Valley at Kaliadem village, about 4.5 km from the Merapi submit, using a Ground Penetrating Radar (GPR). The upper deposit was studied in its distal reaches, whereas the one below was studied in its medial reaches. The field study was carried out with a commercial RAMAC (R) GPR coupled with 100 MHz antennas, and the data treatment conducted with Reflex (TM) software. From this survey, we determined both deposits' local (1) thickness - reaching a maximum of 15 m - and (2) internal architecture. This last one is governed by long reflecting horizons extending over 20 to 30 m that delimit layers showing progradation patterns in their distal reaches. Within these layers we could also observe an internal architecture of still unknown origin. The layers are interpreted as the result of the flow pulses that progressively deposited downstream-ward by progradation. However the interpretation of those GPR profiles is a bit hazardous, because of the absence of outcrops, and we can only proceed by analogy with other studies. Nevertheless, despite numerous limitations, GPR is a helpful tool to understand pyroclastic deposits' structure when no visual observations are available. (C) 2008 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Oct. 2008, JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 176 (4), 439 - 447, English

    [Refereed]

    Scientific journal

  • Reconstruction of Tsunami Inland Propagation on December 26, 2004 in Banda Aceh, Indonesia

    LAVIGNE F, PARIS R, GRANCHER R, WASSMER P, BRUNSTEIN D, VAUTIER F, LEONE F, FLOHIC F, DE COSTER B, GOMEZ C, GUNAWAN, SETIAWAN A, CAHYADI R, FACHRIZAL

    2008, Pure and Applied Geophysics, 165, 1 - 63, English

    [Refereed]

    Scientific journal

  • Field observations of the 17 July 2006 Tsunami in Java

    F. Lavigne, C. Gomez, M. Giffo, P. Wassmer, C. Hoebreck, D. Mardiatno, J. Prioyono, R. Paris

    The 17 July 2006, a tsunami struck the southern coast of Java, Indonesia, causing over 730 casualties. The triggering earthquake located 225 km off the coast of Pangandaran (9.222 degrees S, 107.320 degrees E), occurred at 15:19 LT (UTC +7) with a 7.7 magnitude on the Richter scale (Harward Center and CEA/DAM). In order to calibrate numerical models and understand the phenomenon, we conducted a 6-weeks field survey in July and August 2006 from Cimerak district in West Java to Gunung Kidul district in Central Java. Data collection involved measurements of wave height before its breaking, flow depth, run-up height, inundation depth, flow directions and a detailed chronology of the tsunami. Eyewitnesses accounted for three main waves. The maximum height of the second wave ranged from 4.2 to 8.6 m before its breaking. Maximum flow depth after the wave's breaking reached 5 m, and maximum runup heights reached 15.7 m. Our run-up values are about 1.5 higher than those obtained by the other field surveys carried out until present. They are also higher than the values computed through preliminary models. The 17 July 2006 tsunami has been generated by a "tsunami earthquake", i.e. an earthquake of low or medium scale that triggers a tsunami of high magnitude. The run-up heights progressively decreased eastwards, which is consistent with a tsunami triggered by fault dislocation, as the one that hit the Nicaragua's coast with similar run-up heights on the 2 September 1992. An earthquake with associated landslides could also have generated the 17 July 2006 tsunami, as ever observed in Papua-New-Guinea in 1998.

    EUROPEAN GEOSCIENCES UNION, 2007, NATURAL HAZARDS AND EARTH SYSTEM SCIENCES, 7 (1), 177 - 183, English

    [Refereed]

    Scientific journal

  • Learning from a major disaster (Banda Aceh, December 26th 2004): A methodology to calibrate simulation codes for tsunami inundation models

    Franck Lavigne, Raphael Paris, Patrick Wassmer, Christopher Gomez, Daniel Brunstein, Delphine Grancher, Franck Vautier, Junun Sartohadi, Anggri Setiawan, Taufik Gunawan Syahnan, Budi Waluyo Fachrizal, Djati Mardiatno, Adi Widagdo, Rino Cahyadi, Nicolas Lespinasse, Laurent Mahieu

    This paper... aims at presenting the methods and the preliminary results of the TSUNARISK French-Indonesian programme that run two years in 2005 and 2006. The main goals of this programme are to establish a very complete database of tsunami evidences and to simulate the December 26(th), 2004 tsunami at the Banda Aceh and Lhok Nga districts, Sumatra. Therefore we present a field data based methodology to calibrate simulation codes for tsunami inundation models, and an original flow direction geostatistical model based on fields observations and remote sensing. The inputs provided by seven field trips include field measurements of wave heights and runups (300 points), flow directions (1066 points), chronology of the events, bathymetric and topographic surveys. This worldwide unique database will help calibrating numerical models on high intensity tsunamis.

    GEBRUDER BORNTRAEGER, 2006, TSUNAMIS, HURRICANES AND NEOTECTONICS: AS DRIVING MECHANISMS IN COASTAL EVOLUTION, 146, 253 - +, English

    [Refereed]

    International conference proceedings

  • GEOMORPHOLOGY AND SEDIMENTARY STRUCTURES OF UPPER PLEISTOCENE TO HOLOCENE ALLUVIUM WITHIN THE NYABARONGO VALLEY (RWANDA). PALAEO-CLIMATE AND PALAEO-ENVIRONMENTAL IMPLICATIONS

    Patrick Wassmer, Dominique Schwartz, Christopher Gomez, Stephen Ward, Pierre Barrere

    At the confluence of the Nyabarongo River with the Mukungwa River, to the North of present Rwanda, there are thick alluvial sedimentary sequences, which can reach 30 m in thickness, where they are capped by tufa deposits. From these deposits, two different sedimentary sequences have been identified, with.(i) a first sedimentation stage characteristic of an obstructed valley controlled by contrasted seasonal flows during a dryer and cooler climate than at present, and (ii) on top of this unit a more recent sequence of alluvial terraces that were emplaced during a wetter and warmer context allowing the development and stabilisation of the rainforest. Palynological data and their comparison with a database at the East African regional scale have proven that the first rapid sedimentation stage started around 40,000 BP and might have ended abruptly around 14,000 BP. This process has been then followed by a natural embanking stage of the alluvial corridor. These different terraces have been dated thanks to a series of proxies: the discovery of a Stenoece animal remains in the upper part of a terrace confirmed the palaeo-origin of the sequence; a bone harpoon with typical manufacturing characteristics that indicated a human settlement around 9,000 BP on another terrace; and the tufa deposits provided a maximum age for the terraces below 7,000 years. This multi-proxy approach, therefore, provides an interesting series of benchmarks for the development of the palaeoenvironment in Northern Rwanda and is of high importance for the reconstruction of the river bio-geomorphological adaptation to climatic changes.

    COMITATO GLACIOLOGICO ITALIANO, 2013, GEOGRAFIA FISICA E DINAMICA QUATERNARIA, 36 (1), 199 - 210, English

    [Refereed]

    Scientific journal

  • Akira Kato, Justin Morgenroth, David Kelbe, Christopher Gomez, Jan van Aardt

    Forest monitoring for environmental policy requires accurate and efficient ground-truthing techniques in the field. In this paper, a portable terrestrial laser scanner (TLS) is utilized to estimate leaf area index (LAI) of mixed forest stands in Christchurch, New Zealand. Our method converted laser XYZ coordinates to orthographic coordinates to create fish-eye images, from which LAI was estimated. The results were highly correlated with LAI estimates from three traditional techniques: radiation obtained by AccuPAR (R-2 = 0.81), Landsat TM (R-2 = 0.79), and fish-eye lens photography (R-2 = 0.91). This novel technique is a simple and efficient way to collect and analyze LAI and provides good ground truth data for satellite remote sensing.

    IEEE, 2013, 2013 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS), 2106 - 2109, English

    [Refereed]

    International conference proceedings

  • High-resolution Point-cloud for Landslides in the 21st Century: from data acquisition to new Processing Concepts

    GOMEZ Christopher, ALLOUIS Tristan, LISSAK Candide, HOTTA Norifumi, SHINOHARA Yoshinori, HADMOKO, Danang, VILIMEK Vit, WASSMER Patrick, LAVIGNE Franck, SETIAWAN Angri, SARTOHADI Junun, SAPUTRA Aditya, RAHARDIANTO Trias

    Dec. 2020, World Landslide Forum 5 Publication, English

    [Refereed][Invited]

    In book

  • Improved nomenclature schemes for Component Fault Trees and State/Event Fault Trees

    K. B. Jamboti, C. Gomez, O. Maeckel, P. Liggesmeyer

    Fault tree analysis is a widely applied technique that is used in quantitative and qualitative analysis to obtain information about safety of a system. When fault tree events are named, ambiguous nomenclature can create significant impact on the analysis which then yields erroneous results. We emphasize on the usage of correct nomenclature for fault tree events and describe the effects of the failure to do so. Component Fault Tree (CFT) is a type of improvised fault tree used in industries such as the gas turbine and the railway industry. While conducting analysis of CFTs for systems which are part of a product line in an industrial setting, we discovered that, the same basic events had different properties in different products of a product line. This shows that the existing naming convention is not sufficient for unambiguous nomenclature of FT events. Hence, we extend the present naming convention to address such cases. State/Event Fault Trees (SEFTs) are improvised CFTs which enable one to express the state-based failure behavior which was previously not possible by CFTs. We further extend the naming convention for CFTs with an extra field for SEFTs which takes into account the states and events of a component that can be accessed through its outports. Lastly, we illustrate how the naming convention can be applied to a part of SGT 400, a gas turbine developed by Siemens AG, Munchen.

    CRC PRESS-TAYLOR & FRANCIS GROUP, 2014, SAFETY, RELIABILITY AND RISK ANALYSIS: BEYOND THE HORIZON, 145 - 151, English

    [Refereed]

    International conference proceedings

  • JP Le Roux, C Gomez, J Fenner, H Middleton

    Exceptionally good outcrops of Miocene to Pliocene deposits in the vicinity of submarine Paleozoic basement scarps at Carrizalillo, north of La Serena, reveal a wealth of sedimentary features not commonly observed. The most proximal facies consist of rock fall and coarse-grained debris flow deposits directly abutting the basement wall from which they originated. Angular basement clasts are mixed with well-rounded cobbles, which probably formed as a basal gravel on a wave-cut platform at the beginning of marine flooding, subsequently accumulated at the scarp edge and were incorporated into the debris when the latter collapsed. The poor sorting, inverse grading, and protruding cobbles and boulders are classical debris flow features, with good clast imbrication indicating a laminar shearing action. A medial facies is represented by secondary channels running parallel to the major scarp about 1 km downslope of the first locality. In the largest channel, megaflutes at the base indicate the passage of highly turbulent, nondepositing flows eroding the soft, silty substrate. In the deepest, central part of the channel, a pebbly coquina shows horizontal and trough cross-stratification, with most of the bivalves oriented convex side up. Meter-scale rip-up clasts of the underlying siltstone are also present, indicating turbulent flow with a density sufficiently high to retard settling. The coquina is interpreted as a detachment deposit resulting from a hydroplaning debris flow along the central part of the channel, where the velocity and rate of pore pressure decay were highest. This deposit is overlain by fining upward, massive to horizontally stratified sandstone very similar in texture and composition to the matrix of the debris flow, suggesting its formation by surface transformation and elutriation of the latter. Along the channel margin, a basal centimeter-scale sandstone layer is virtually unaffected by the megaflute topography and clearly represents a subsequent event. It is interpreted as a basal shear carpet driven by the overlying debris flow. Within the shear carpet, a basal friction zone and an overlying collision zone containing a higher concentration of shell hash can be distinguished. The overlying debris flow deposit is represented by massive coquina with scattered, angular to rounded basement clasts. It contains disarticulated bivalves oriented with their concave side up, indicating large-scale upward fluid escape during deposition. A smaller secondary channel shows large rip-up rafts of the underlying substrate. Some rafts appear to have been plucked from the substrate by a process of sand injection from an overriding high-density sandy debris flow, which probably originated during a tsunami. Such clasts can climb upward into a laminar flow by down-current tilting and tumbling. The most distal facies occurs below a second scarp oriented more or less parallel to the present coastline, where finer-grained turbidites onlap and backlap onto the stoss and lee sides of an obstacle formed by eroded boulder conglomerates. The onlap deposits resemble inclined sandy macroforms recently described in submarine canyon settings. They are interbedded with diatom-containing, volcanic ash beds with cross-stratification dipping eastwards and containing deepwater microflora typical of continental upwelling zones. (C) 2004 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Mar. 2004, SEDIMENTARY GEOLOGY, 165 (1-2), 67 - 92, English

    [Refereed]

    Scientific journal

  • C Gomez, C Delacourt, P Allemand, P Ledru

    The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) launched on NASA's Terra satellite ranks lately among potential tools for Earth Observation. ASTER measures reflected radiations in 3 bands between 0.52 to 0.86 mum (VNIR) and in 6 bands between 1.6 to 2.43 mum (SWIR). An ASTER image has been acquired on the Southern margin of the Damara orogen (Namibia, northern margin of the Nama marine sedimentary sequence) essentially composed by limestone, sandstone and shale. Furthermore, a program initiated by the Geological Survey of Namibia has permitted to obtain a radiometric data set (Thorium, Uranium and Potassium) of Rehoboth region in Namibia. The combined ASTER and airborne geophysical data have been processed and interpreted for improving the existing geological map. First, a Principal Component Analysis (PCA) on the 9 ASTER bands is realised and only the first five components are kept. Then, the Maximum Likelihood approach is used to identify lithological formations from radiometric data and PCA components. Importance of random training data has been pointed out. Finally the coupling of ASTER and radiometric data is the best approach for the improvement of geological map with a proportion of correctly mapped surface of 63.4% from initial geological map.

    SPIE-INT SOC OPTICAL ENGINEERING, 2004, REMOTE SENSING FOR ENVIRONMENTAL MONITORING, GIS APPLICATIONS, AND GEOLOGY III, 5239, 98 - 108, English

    [Refereed]

    International conference proceedings

  • Patrick Wassmer, Jean-Luc Schneider, Anne-V. Fonfrege, Franck Lavigne, Raphaeel Paris, Christopher Gomez

    We studied emplacement dynamics of the December 26, 2004 tsunami deposits in artificial shallow ponds and in shallow lagoons, along the northern coast of Sumatra in Banda Aceh area. Successive tsunami waves inundated topographic lows, which acted as sediment traps and favored preservation of deposits. Individual waves led to the deposition of fining upwards sedimentary sequences. This multiple normal grading deposit with a thickness ranging from 2 to 80 cm constitutes a site of major interest for the study of the deposits emplaced by a tsunami wave train. The main interest lies in the characteristics of the deposits that can be correlated to the behavior of the waves attested by numerous testimonies. In this setting, we aimed at testing the applicability of the AMS (Anisotropy of Magnetic Susceptibility) technique as a proxy of unconsolidated sediment fabric. The combination of this proxy and traditional sedimentary analysis helped reconstructing the hydrodynamic conditions particularly the flow direction, prevailing during sedimentation. We applied the AMS technique on eight sections stretching inland from 1.5 km to 2.2 km from the pre-tsunami coastline. Grain-size and AMS data from these deposits provide similar and partially complementary information. Traction dominates in the basal parts of the deposits and occurs mainly for the basal layers of the sequences whereas settling dominates for the upper layers of these sequences. The vertical evolution of the AMS parameters within the deposits is related to the arrival of the successive waves with variations in the traction and decantation processes during deposition. Variations of current strength during sedimentation are related to the wave's momentum and to the progressive infill of topographic depressions. The vertical change of the fifth coarsest percentile vs. the median grain sizes of the deposits suggests strong variations of the energy of the currents, and confirms the evolution of the AMS parameters. In the present study, the fabric of the deposits, which developed exclusively during the uprush phase of the cycle, also allows the reconstruction of flood directions that are both normal and parallel to the shoreline, with variations related to flow dynamics, mean grain size and local topographic control. Due to the absence of backwash in between the waves and low velocity of the final backwash, information about the sedimentation conditions of the tsunami deposits appears to be better preserved in topographic depressions in areas located remote from the seashore. The AMS proxy appears to be a promising tool for further studies of recent- and paleo-tsunami deposits. (C) 2010 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Sep. 2010, MARINE GEOLOGY, 275 (1-4), 255 - 272, English

    [Refereed]

    Scientific journal

  • JP Le Roux, C Gomez, C Venegas, J Fenner, H Middleton, M Marchant, B Buchbinder, D Frassinetti, C Marquardt, KM Gregory-Wodzicki, A Lavenu

    The stratigraphy, sedimentology, and paleontology of the Coquimbo Formation in a coastal section approximately 100km north of La Serena was Studied to establish relative low-order sea-level changes during the Neogene. During the Early-Middle Miocene, a wide coastal platform was bevelled onto Palaeozoic basement rocks, and marine sedimentation may have taken place within a deep coastal inlet later transformed into a submarine canyon. Transgression over this platform commenced during the late Burdigalian-early Langhian (16-15 Ma) and culminated in a sea-level highstand near the end of the Serravalian (11.8 Ma). This transgression was followed by regression during the rest of the Serravalian and Tortonian until approximately 9 Ma. Renewed transgression during the Messinian was Succeeded by regression lasting until 5.5 Ma, when another transgressive cycle bevelled a ravinement Surface into the underlying deposits. This cycle terminated in a marine highstand during the Zanclean at 4.9 Ma. Thereafter, the succession changed front enter platform to middle shoreface deposition. Rapid flooding at 3.9 Ma resulted in the formation of an extensively bored phosphatic hardground, which represents a condensed section. A lowstand during the Piacenzian is represented by inner-shelfdeposits, followed by a return to outer-shelf deposition with contemporaneous upper continental slope sedimentation below the ancient shell'break. The succession is capped by Gelasian upper shoreface deposits dated at 2.0-1.8 Ma. The reemergence of the shelf during the Pleistocene (1.0 Ma) formed an extensive coastal plain covered by fluvioestuarine, shelly gravel. Subsequently, four marine terraces were carved into the Succession in the last 0.5 Ma. A comparison of the recorded sea-level changes with global sea-level Curves provides a reconstruction of local tectonic uplift and downwarp events during the Neogene-Quaternary. The migration of the Juan Fernandez Ridge underneath this part of the Chilean flat-slab sectorcaused a relative uplift of 60 m, followed by subsidence of 125 m in its wake. The generalized tectonic rate of change varied front 0.02 to 0.08 mm/yr. (c) 2005 Elsevier Ltd. All rights reserved.

    PERGAMON-ELSEVIER SCIENCE LTD, May 2005, JOURNAL OF SOUTH AMERICAN EARTH SCIENCES, 19 (1), 83 - 98, English

    [Refereed]

    Scientific journal

  • C Gomez, C Delacourt, P Allemand, P Ledru, R Wackerle

    The present study deals with the estimation of the advanced spaceborne thermal emission and reflection radiometer (ASTER) data for geological application. Visible, near-infrared and short wave infrared reflectance data (9 ASTER bands) have been processed and interpreted in framework of a mapping project concerning the western margin of the Kalahari desert. A methodology has been applied to apparent reflectance images corrected to illumination effects. A Principal Component Analysis (PCA) has been realised on the 9 ASTER bands in order to reduce the redundancy information in highly correlated bands. PCA results enable the validation and the revision of the lithological boundaries defined on previous geological map and provide information for characterising new lithological units corresponding to surficial formations previously unrecognised. A supervised classification realised from PCA results and based on the geological map shows that lithological units may have similar spectral signature, a strong spectral variability or a spectral homogeneity. The processing of ASTER remote sensing data set can thus be used as a powerful tool for geological mapping. (C) 2004 Elsevier Ltd. All rights reserved.

    PERGAMON-ELSEVIER SCIENCE LTD, 2005, PHYSICS AND CHEMISTRY OF THE EARTH, 30 (1-3), 97 - 108, English

    [Refereed]

    Scientific journal

  • Remote Sensing for mass Movement Assessment

    Lissak, C, Bartsch, A, Roucoules, M, Gomez, C, Maquaire, O

    Sep. 2020, Survey in Geophysics, English

    [Refereed]

    Scientific journal

  • Aditya Saputra, Christopher Gomez, Ioannis Delikostidis, Peyman Zawar-Reza, Danang Sri Hadmoko, Junun Sartohadi

    Informa UK Limited, 07 Aug. 2020, Geo-spatial Information Science, 1 - 23

    [Refereed]

    Scientific journal

MISC

  • Sustainability of three modified soil conservation methods in agriculture area

    SETIAWAN M.A, SARA H.S, CHRISTANTO N, SARTOHADI J, SAMODRA G, WIDICAHYONO A, WIDIYATI C.N, ASTUTI E.M, MARTHA G.K, MALIK R.F, SAMBODO A.P, ROKHMANINGTYAS R.P, SWASTANTO G.A, GOMEZ ANDRE CHRISTOPHER

    Nov. 2017, ICERM Conference Proceedings (Bali, Indonesia), English

    [Refereed]

    Introduction international proceedings

  • TECHNICAL NOTE: Surge Flow CFD at the Curah Lengkong Valley, Semeru Volcano, Indonesia

    GOMEZ C

    Sep. 2017, Volcanic Risks at Sea Technical Note 001 HAL-01586875, English

    Technical report

  • Earthquake Disturbances

    MARSDEN I, HART, D.E, REID C, GOMEZ C

    Last, 2016, The Encyclopedia of Estuaries, English

    [Refereed][Invited]

    Book review

  • Structure from Motion and Wavelet Decomposition for outcrop analysis.

    GOMEZ C

    2014, Hyper Archives en Ligne, hal-00939994.15pp., English

    Technical report

  • Interactions between Slopes and Lake Sedimentary Processes: Study from Aerial Imagery and Ground Penetrating Radar Survey in the Alps of New Zealand

    MILLER J, GOMEZ C, PURDIE H

    2014, Hyper Archives en Ligne, 45p., English

    Technical report

  • Agriculture Irrigation in the Canterbury Plains – New Zealand: Assessment from Landsat Imagery Remote Sensing

    HARRISON M, GOMEZ C

    2014, Hyper Archives en Ligne, hal-00933711. 50pp, English

    Technical report

  • The Spatial Distribution of Large Woody Debris and Its Relationship with Channel morphology in the Bitterroot River, Montana.

    BERGMEIER M, CLARK M, MARTIN A, SHERIDAN M, GOMEZ C

    2013, Hyper Archives en Ligne, http://hal.archives-ouvertes.f, English

    Technical report

  • C. L. Kain, C. Gomez, A. E. Moghaddam

    Studies of coastal boulder deposits have dramatically increased in number during the last decade. These have been accompanied by modeling efforts to understand the initiation of transport and the transport itself. A recent article by Nandasena et al. (2011) has attempted to improve equations developed by Nott (1993, 2007) for the movement initiation of boulders, but we argue that these equations are not appropriate for the tsunami data (at least in North Sumatra) used to reassess Nott's set of equations. Indeed, the field work on which the discussed article is partially based is inconsistent with the findings. The sand-beach context and the distribution of these boulder deposits may invalidate the modeling approach of the authors. It is very unlikely that water alone was able to initiate the transport of the limestone clasts. The role of the smaller fractions must be assessed as these were an important component of the 2004 Boxing Day tsunami waves. Moreover, the spatial distribution of the boulder deposits, which part of the discussed article relies on and that has been described in a previous paper, is not consistent with the inferences drawn in the present article. The deposit has been described as a mix of boulders of various sizes and weight concentrated in space, without landward fining. This suggests an 'en masse' deposit rather than a deposit related to a progressive reduction of water velocity. Such 'en masse' deposits have been related in different environments to 'debris-flows'. Hence, we suggest that this modeling needs to take into account smaller sediments and eventually move towards a Bingham flow concept for the case of tsunami waves. (C) 2012 Elsevier B.V. All rights reserved.

    ELSEVIER SCIENCE BV, Aug. 2012, MARINE GEOLOGY, 319, 75 - 76, English

    Others

Books etc

  • Structure from Motion for Outcrop Study

    SAPUTRA A, GOMEZ ANDRE CHRISTOPHER

    Single work, Earth Crust (InterTech Open Pub. London), Dec. 2018, English

    Scholarly book

  • Geotourism risk Management

    PURDIE H, GOMEZ CHRISTOPHER ANDRE, ESPINER S

    Others, Handbook of Geotourism, Dec. 2017, English

    Textbook

  • Ethics and Disaster Risk Reduction including Climate Change adaptation

    GOMEZ CHRISTOPHER ANDRE

    Others, The Routledge Handbook of Disaster Risk Reduction Including Climate Change Adaptation, 2017, English

    Textbook

  • The Environmental Framework of the Si Pamutung Archaeological Site

    LAVIGNE F, LESPINASSE N, GOMEZ CHRISTOPHER ANDRE

    Others, D. Perret and H. Surachman (Ed.), The Settlement of Si Pamutung in Padang Lawas, North Sumatra (9th-13th centuries CE), 2012, English

    Textbook

  • PR Investigation of the Si Pamutung Site, Central Sumatra, Indonesia

    LAVIGNE F, LESPINASSE N, GOMEZ CHRISTOPHER ANDRE

    Others, D. Perret and H. Surachman (Ed.), The Settlement of Si Pamutung in Padang Lawas, North Sumatra (9th-13th centuries CE), 2012, English

    Textbook

  • L'apport du Radar Geologique pour l'etude des impacts geomorphologiques du tsunami du 26 Decembre 2004

    GOMEZ ANDRE CHRISTOPHER, LAVIGNE F, LESPINASSE N

    Joint work, Le Tsunami du 26 Decembre 2004, Publications de la Sorbonne, Paris., 2010, French

    Scholarly book

  • 2004 tsunami deposits’ erosion revealed by GPR survey (Banda Aceh – Indonesia)

    GOMEZ ANDRE CHRISTOPHER, LESPINASSE N, LAVIGNE F, SAINTENOY A

    Single work, TSUNARISQUE, Paris 1 Sorbonne University Press, 2006, French

    Scholarly book

Presentations

  • In-flow Sediment Fragmentation of Debris-flow Material - Rolling Tumbler Experiments with Stratovolcanic Dacite -

    GOMEZ ANDRE CHRISTOPHER, Hotta, N, Shinohara, Y, Tsunetaka, H

    9th International Workshop on Multimodal Sediment Disasters, Oct. 2019, English, International conference

    Oral presentation

  • GPR Imaging of Moisture and Water Movement in Volcanic Soil

    GOMEZ ANDRE CHRISTOPHER

    Japanese Geophysical Union Meeting 2019, Jun. 2019, English, International conference

    Oral presentation

  • Application of the self-potential method for evaluating subsurface structure of potential sites for deep-seated landslides

    YAMAKAWA, Y, GOMEZ ANDRE CHRISTOPHER, MASAOKA, N, KOSUGI, K

    130回日本森林学会大会, May 2019, Japanese, Domestic conference

    Oral presentation

  • Grain-size Distribution Change at Unzen Volcano and Impact on Lahar Triggering and Flowage

    GOMEZ ANDRE CHRISTOPHER, Hotta, N, Shinohara, Y, Tsunetaka, H

    2019 Annual Sabou Gakkai, May 2019, English, International conference

    Oral presentation

  • Drifted Wood Distribution in Asakura (Kyushi) following the 2017 rain-triggered Debfirs-Flows and Landslides

    Lissak, C, GOMEZ ANDRE CHRISTOPHER, Shimizu, M, Hotta, N, Davidson, R, Uchida, T

    European Geophysical Union (Vienna), May 2019, English, International conference

    Oral presentation

  • Climate Change and Population Depletion Control over Sediment Hazard and Drifted Wood Hazards in Japan

    Shimizu, M, GOMEZ ANDRE CHRISTOPHER, Uchida, T

    Sabou Gakkai Annual Conference 2019, May 2019, Japanese, International conference

    Poster presentation

  • 3d Surface Roughness Analysis of Tree Barks as a Proxy of Potential Radioactive Material Absorption

    Matsui, H, GOMEZ ANDRE CHRISTOPHER

    CRIED Annual Symposium 2019, Mar. 2019, Japanese, International conference

    Poster presentation

  • Understanding Numazawa Breakout Flood for Disaster Management - Ground Penetrating Radar Perspectives

    GOMEZ ANDRE CHRISTOPHER, Kataoka, K

    Niigata University, Institute for Natural Hazards and Disaster Recovery Conference, Feb. 2019, Japanese, Domestic conference

    Oral presentation

  • Open Seminar: Ground Penetrating Radar for Bio- Sedimentological Hazards and Disaster Risk Assessment from examples in Indonesia and in Japan: an Essential Complement to Geodetic Analysis

    GOMEZ ANDRE CHRISTOPHER

    Ecosystem Ecology Seminar at Hyogo University, Sep. 2018, English, Domestic conference

    Invited oral presentation

  • The Asakura Sediment and Tree Disaster: Drifted Wood Distribution and Flow Dynamics from UAV and aircraft Remote Sensing

    GOMEZ ANDRE CHRISTOPHER

    Tsukuba Ministry of Land, Infrastructure and Transport - SABO divison, Jun. 2018, Japanese, Domestic conference

    Public discourse

  • Stem flow and water distribution around trees from SfM-based Micromorphometry

    GOMEZ ANDRE CHRISTOPHER

    CRIED 2018 Collaborative Research Symposium, Jun. 2018, English, International conference

    Oral presentation

  • Earthquake and Stormwater lifelines: a method for revealing multi-hazard interactions to improve engineering resilience

    HART D, GOMEZ ANDRE CHRISTOPHER, GIOVINAZZI S, DAVIES C

    16th European Conference on Earthquake Engineering (16ECEZ), Jun. 2018, English, Thessaloniki, Greece, International conference

    Oral presentation

  • Valley Morphological Control of Drifted Wood and Debris - the 2017 mass-movements and floods in Kyushu

    GOMEZ ANDRE CHRISTOPHER, HOTTA N, SHINOHARA Y, TSUNETAKA H

    Japan Geoscience Union Meeting 2018 (Makuharimesse, Japan), May 2018, English, International conference

    Oral presentation

  • The role of DEM resolution on ballistic distribution using the BALLISTA model at Merapi Volcano

    GOMEZ ANDRE CHRISTOPHER, TSUNEMATSU, K

    Japan Geoscience Union Meeting 2018 (Makuharimesse, Japan), May 2018, English, International conference

    Oral presentation

  • Statistical Analysis of the Distribution of Ballistic Deposits using BALLISTA Model

    TSUNEMATSU K, KENNEDY B.M, GOMEZ ANDRE CHRISTOPHER, FITZGERALD R, CHOPARD B

    Japan Geoscience Union Meeting 2018 (Makuharimesse, Japan), May 2018, English, International conference

    Oral presentation

  • Shallow Landslides & Drifted Wood Hazards following the July 2017 Rainfall Event in Kyushu

    GOMEZ ANDRE CHRISTOPHER, HOTTA N, SHINOHARA Y, TSUNETAKA H, LISSAK C, SHIMIZU M

    5th International Symposium on Mega Earthquake induced Geo-disasters, May 2018, English, International conference

    Oral presentation

  • Seismic vulnerability assessment of residential buildings using probabilistic model of logistic regression and geographic information system (GIS) in Pleret Sub District, southeast part of the Yogyakarta City.

    SAPUTRA A, RAHARDIANTO T, REVINDO M.D, DELIKOSTIDIS I, GOMEZ ANDRE CHRISTOPHER

    Japan Geoscience Union Meeting 2018 (Makuharimesse, Japan), May 2018, English, International conference

    Poster presentation

  • Moving Japan Scientific Scene into the 21st Century: the need of Ecofeminism for Emerging Diversity and Minorities

    GOMEZ ANDRE CHRISTOPHER

    Japan Geoscience Union Meeting 2018 - Invited Talk, May 2018, English, International conference

    Keynote oral presentation

  • Liquefaction at the Kobe University Campus during the Awaji-Hanshin Earthquake – Evidence from Ground Penetrating Radar

    SAKAMOTO M, SHIMIZU M, IMAI K, MATSUI H, GOMEZ C

    Japan Geoscience Union Meeting 2018 (Makuharimesse, Japan), May 2018, English, International conference

    Poster presentation

  • Implementation of Selection Criteria to Improve Landslide Susceptibility Model of Kashiwazaki-Kariwa, Japan: a Frequency Ratio Approach

    RAHARDIANTO T, GOMEZ ANDRE CHRISTOPHER, WILSON M

    Japan Geoscience Union Meeting 2018 (Makuharimesse, Japan), May 2018, English, International conference

    Poster presentation

  • Glacier Recession Uncorks Sediment Transfer at Fox Glacier (NZ)

    GOMEZ ANDRE CHRISTOPHER, PURDIE H

    5th International Symposium on Mega Earthquake induced Geo-disasters, May 2018, English, International conference

    Oral presentation

  • Dome Evolution at Unzen Volcano between 2003 and 2015

    GOMEZ ANDRE CHRISTOPHER, HOTTA N, SHINOHARA Y

    5th International Symposium on Mega Earthquake induced Geo-disasters, May 2018, English, International conference

    Oral presentation

  • Differentiating Transport Mechanism of Pumices in Hyperconcentrated-flows from Numazawa Volcano – Japan

    GOMEZ ANDRE CHRISTOPHER, KATAOKA K

    Japan Geoscience Union Meeting 2018 (Makuharimesse, Japan), May 2018, English, International conference

    Oral presentation

  • Determining earthquake susceptible areas Southeast of Yogyakarta, Indonesia – Outcrop analysis from structure from motion (SfM) and geographic information system (GIS)

    SAPUTRA, A, DELIKOSTIDIS I, HADMOKO SRI D, SARTOHADI J, ZAWAR-REZA P, GOMEZ ANDRE CHRISTOPHER

    Japan Geoscience Union Meeting 2018 (Makuharimesse, Japan), May 2018, English, International conference

    Poster presentation

  • Ballistic Hazards Simulation at Merapi Volcano – Indonesia – using BALLISTA

    GOMEZ ANDRE CHRISTOPHER, TSUNEMATSU, K, DJATI, SETIAWAN A, SARTOHADI J, SRI HADMOKO D

    Japan Geoscience Union Meeting 2018 (Makuharimesse, Japan), May 2018, English, International conference

    Oral presentation

  • The Spatio-temporal control of pumice vesicularity on lahar disaster risks

    GOMEZ ANDRE CHRISTOPHER

    平成29年度 新潟大学災害・復興科学研究所共同研究成果報告会, Mar. 2018, English, International conference

    Oral presentation

  • Pumiceous Ignimbrite Material Affects on Giant Lahar Rheology from Numazawa Volcano, Japan

    GOMEZ ANDRE CHRISTOPHER, KATAOKA K

    2018 Symposium of the Research Institute for Natural Hazards and Disaster Recovery, Mar. 2018, English, Domestic conference

    Oral presentation

  • Deciphering Tsunami & Paleo-tsunami Waves Energy and Orientation at the Coast using Anisotropy of Magnetic Susceptibility: Research in Japan, Indonesia and New Zealand

    GOMEZ ANDRE CHRISTOPHER

    (Invited Lecture) 海事防災研究会, Mar. 2018, English, Domestic conference

    Invited oral presentation

  • High -Resolution and -Frequency Topographic Data: Opportunities and Limitations to Solve 21st Century Challenges in Rural Japan

    GOMEZ ANDRE CHRISTOPHER

    2017年12月13日水曜日 第9回GIS-Landslide研究集会および第5回高解像度地形情報シンポジウム, Feb. 2018, English, Domestic conference

    Invited oral presentation

  • Assessing ballistic hazard using a UAV: Yasur Volcano, Vanuatu

    FITZGERALD R, KENNEDY B, GOMEZ ANDRE CHRISTOPHER, WILSON T, LEONARD G, JOLLY A, MATOZA R, FEE D, AUSTIN A, IEZZI A, SIMONS B, KILGOUR G

    Cities on Volcanoes 2018 S1.5 Geomatics and volcanic areas monitoring, 2018, English, International conference

    Oral presentation

  • TUTORIAL: Drone-based Photogrammetry - from Data Collection to Data Processing

    GOMEZ ANDRE CHRISTOPHER

    Universitas Muhammadyah Surakarta, Oct. 2017, International conference

    Public discourse

  • Structure from Motion and Multiple View Stereophotogrammetry - methodology and novel approaches for Indonesia

    GOMEZ ANDRE CHRISTOPHER

    Seminar at Pak Angry Laboratory of Geomorphology, Universitas Gadjah Madah, Oct. 2017, English, International conference

    Public discourse

  • Mahasiswa UMS Dapat Transfer Ilmu Kebencanaan dari Dosen Jepang

    GOMEZ ANDRE CHRISTOPHER

    Suara Merdeka (インドネシア), Oct. 2017, International conference

    Media report

  • Living on the Edge: The Role of Geosciences in Rising Indonesia and Climate Change Challenges - Methods and Tools to Solve Present and Future Issues in Indonesia and East Asia -

    GOMEZ ANDRE CHRISTOPHER

    Public Speech - Universitas Muhammadyah Surakarta, Oct. 2017, International conference

    Invited oral presentation

  • Insights from the Editor: Writing and Being Published in Academia

    GOMEZ ANDRE CHRISTOPHER

    Universitas Muhammadyah Surakarta - Invited Lecture to Faculties, Oct. 2017, English, International conference

    Invited oral presentation

  • How to Write Scientific Publications in English - a Method to Publish Successfully

    GOMEZ ANDRE CHRISTOPHER

    Universitas Gadja Madah - Open Presentation, Oct. 2017, English, International conference

    Public discourse

  • Professor from Japan invited at UMS Geography - Providing Exchange Opportunities for Students

    GOMEZ ANDRE CHRISTOPHER

    Jawa Pos (インドネシア), Oct. 2017, International conference

    Media report

  • Ethics in Disaster Risk Management

    GOMEZ ANDRE CHRISTOPHER

    Universitas Gadja Madah - Disaster Risk Management Course, Oct. 2017, English, International conference

    Public discourse

  • 21st Century Challenges in East-Asia, between population transition and climate change, what role for geosciences

    GOMEZ ANDRE CHRISTOPHER

    Invited Public Speech at UGM (Yogyakarta, Indonesia), Oct. 2017, English, International conference

    Invited oral presentation

  • Acoustic Source Waveform Simulation and Inversion at Yasur Volcano, Vanuatu

    IEZZI, A.M, FEE D, KIM K, MATOZA R.S, AUSTIN A, JOLLY A, CHRISTENSON B, JOHNSON R, GARAEBITI E, KENNEDY B, FITZGERALD R, KEY N, TESSIER A, GOMEZ ANDRE CHRISTOPHER

    IAVCEI 2017, Portland, USA, Aug. 2017, English, International conference

    Oral presentation

  • Multihazards in the 21st Century: Why Sciences is in serious need of Leadership and Why Geosciences Education and Research is Primordial

    GOMEZ ANDRE CHRISTOPHER

    Niigata University - Geology Dept. Invited Seminar, Jun. 2017, English, Domestic conference

    Oral presentation

  • Measuring the Earth to Meet 21st Century Challenges: Natural Hazards and Disaster Risks on a Changing Planets with a Changing Population

    GOMEZ ANDRE CHRISTOPHER

    Fuji Architecture Ltd., Jun. 2017, Japanese, Domestic conference

    Oral presentation

  • Guest Seminar: 21st Century Challenges in geosciences

    GOMEZ ANDRE CHRISTOPHER

    千葉大学, May 2017, Japanese, Domestic conference

    Public discourse

  • CFD Modelling of the Local Effects of Caldera Crater Walls and Wind-field Variations on Trapping Potential Harmful Volcanic Gases

    GOMEZ ANDRE CHRISTOPHER

    Japanese Geophysical Union & American Geophysical Union, May 2017, English, International conference

    Poster presentation

  • The application of structure from motion (SfM) to identify the geological structure and outcrop studies

    SAPUTRA A, RAHARDIANTO T, GOMEZ ANDRE CHRISTOPHER

    AIP Conference 2017, Bandung, Indonesia, 2017, English, International conference

    Oral presentation

  • Rockfall Simulation from DSM Data generated by SfM from UAV-based imagery: Analysing the rockfall hazards in the touristic Fox Valley

    HATA H, GOMEZ ANDRE CHRISTOPHER, PURDIE H, TIBBOTTS S, NARAMA C

    Japanese Geophysical Union & American Geophysical Union, 2017, English, Domestic conference

    Poster presentation

  • Potential coping capacities to avoid tsunamis in Mentawai

    PANJAITAN B, GOMEZ ANDRE CHRISTOPHER, PAWSON E

    AIP Conference 2017, Bandung, Indonesia, 2017, English, International conference

    Oral presentation

  • Open Source 3D Multiparticle Ballistic Simulator "Ballista"

    TSUNEMATSU K, FITZGERALD R, KENNEDY B, GOMEZ ANDRE CHRISTOPHER, FALCONE J.-L, CHOPARD B

    IAVCEI 14-18 August 2017 Portland, USA, 2017, English, International conference

    Oral presentation

  • Living on a Donuts - Coastal and Sea Hazards in the age of Climate Change and the Anthropocene

    GOMEZ ANDRE CHRISTOPHER

    15th International Symposium on Geo-disaster Reduction (Invited Speech), 2017, English, International conference

    Oral presentation

  • Finite Volume Method Modelling of Volcanic Ballistic Impacts on Soft Ash and on Buildings - a Hazards Approach

    GOMEZ ANDRE CHRISTOPHER, TSUNEMATSU K

    Japanese Geophysical Union & American Geophysical Union, 2017, English, Domestic conference

    Poster presentation

  • Features of Numerical Model “Ballista”; the Ballistic Simulator of Explosive Volcanic Eruption

    TSUNEMATSU K, GOMEZ ANDRE CHRISTOPHER, FITZGERALD R, KENNEDY B, YAMAOKA K

    Japanese Geophysical Union & American Geophysical Union, 2017, English, Domestic conference

    Oral presentation

  • Fault Mapping at the Confluence of the Aga River and the Tadami River - Japan - using Ground Penetrating Radar

    GOMEZ ANDRE CHRISTOPHER, KATAOKA K

    Institute of Electronics, Information and Communication Engineers (IEICE), Japan - Workshop on GPR Measurements of Active Faults and Tsunami Sediments (French Embassy, Tokyo), 2017, English, Domestic conference

    Oral presentation

  • Eroded Coastal Dune and Deposits in North Sumatra (Indonesia) following the 2004 Boxing Day Tsunami - a Geophysical Approach

    GOMEZ ANDRE CHRISTOPHER

    Institute of Electronics, Information and Communication Engineers (IEICE), Japan - Workshop on GPR Measurements of Active Faults and Tsunami Sediments (French Embassy, Tokyo), 2017, English, Domestic conference

    Oral presentation

  • Development of a New Method for Rockfall Analysis using Schmidt Hammer

    HATA H, GOMEZ ANDRE CHRISTOPHER, NARAMA C

    Japanese Geophysical Union & American Geophysical Union, 2017, English, Domestic conference

    Poster presentation

  • 3D acoustic waveform simulation and inversion supplemented by infrasround sensors on a tethered weather balloon at Yasur Volcano, Vanuatu

    IEZZI A.M, FEE D, MATOZA R.S, JOLLY A.D, KIM K, CHRISTENSON B, JOHNSON R, KILGOUR G, GARAEBITI E, AUSTIN A, KENNEDY B, FITZGERALD R, GOMEZ ANDRE CHRISTOPHER, KEY N

    AGU (American Geophysical Union) Fall Meeting 2017, 2017, English, International conference

    Oral presentation

  • Integrating Multiple Scales and Pluridisciplinary Geomatics to meet the Challenges of the 21st Century.

    GOMEZ ANDRE CHRISTOPHER

    American Geophysical Union - Japanese Geophysical Union Joint Meeting (Keynote Speech), 2016, English, International conference

    [Invited]

    Invited oral presentation

  • Simulating the role of climate change on coastal streams hydrology and sediment dynamics in Christchurch

    GOMEZ ANDRE CHRISTOPHER, HART D, GIOVINAZZI S

    AGU Fall Meeting 2015, Dec. 2015, English, International conference

    Oral presentation

  • Individual and Household Tsunami Preparedness Measures in Mentawai, West Sumatra, Indonesia

    PANJAITAN B, GOMEZ ANDRE CHRISTOPHER, PAWSON E

    New Zealand Asian Studies Society International Conference, Dec. 2015, English, Christchurch, New Zealand, International conference

    Oral presentation

  • Validation of Daily Operational Satellite-based rainfall products over data-sparse Cuvelai Basin (Namibia) using the flood events 2009-2011

    PERSENDT F, GOMEZ ANDRE CHRISTOPHER, ZAWAR-REZA P

    WATERWAYS Conference 2015, Lincoln University, New Zealand, Oct. 2015, English, International conference

    Oral presentation

  • The Anthropocene: observations and expectations for coastal evolution and sedimentary records.

    GOMEZ C

    Geological Society of America 2015, Baltimore, Maryland, USA, Oct. 2015, English, International conference

    Oral presentation

  • Post-disaster research: ethical challenges and opportunities

    GAILLARD J.-C, GOMEZ ANDRE CHRISTOPHER

    11th Association of Pacific Rim Universities Research Symposium and Multi-Hazards around the Pacific Rim, Manila, The Philippines, Oct. 2015, English, International conference

    Oral presentation

  • Modelling the effects of the Christchurch coastal-earthquake on coastal streams using 3D shallow-water equations

    GOMEZ ANDRE CHRISTOPHER, HART D, GIOVINAZZI S

    Geological Society of America 2015, Baltimore, Maryland, USA, Oct. 2015, English, International conference

    Oral presentation

  • Rockfall at Fox Glacier, New Zealand: a Hazard Analysis using Structure from Motion and Spatial Modelling.

    ROY E.S, PURDIE H, GOMEZ ANDRE CHRISTOPHER, WASSMER P, SCHUSTER M

    ICGdR 14th International Symposium on Geo-disasters, Aug. 2015, English, International conference

    Oral presentation

  • Preliminary Report of the AMS Analysis of the Tsunami Deposit in Tohoku – Japan

    WASSMER P, GOMEZ ANDRE CHRISTOPHER, HART D.E, HIRAISHI T, AZUMA R, KOENIG B, TRAUTMAN M

    ICGdR 14th International Symposium on Geo-disasters, Aug. 2015, English, International conference

    Oral presentation

  • Unmanned Autonomous Vehicles for mapping complex evolving events: applications in quantitative earth surface processes and disaster prevention.

    GOMEZ ANDRE CHRISTOPHER

    Helsinki University - College of Sciences Invited Speech, 2015, English, International conference

    Oral presentation

  • The 2011 Earthquake in Christchurch: Remote Sensing and GIS Analysis of a Multiscale problem

    GOMEZ ANDRE CHRISTOPHER

    Kyoto University DPRI (21 Dec. 2015), 2015, English, Domestic conference

    Public symposium

  • Structure from Motion Point Cloud: a Rapid and Low-Cost Alternative to Laser Technologies.

    GOMEZ ANDRE CHRISTOPHER

    Helsinki University - Geocomputing Group (Invited talk), 2015, English, International conference

    Oral presentation

  • Solving Multihazards Problems in the City with Geospatial Technologies, in the light of Climate change Issues

    GOMEZ ANDRE CHRISTOPHER

    Tokyo University CSIS Invited Seminar, 2015, English, Domestic conference

    Oral presentation

  • Environmental change, geo-hazards and disasters in coastal cities: the new challenges.

    GOMEZ ANDRE CHRISTOPHER

    Universitas Gadja Madah (invited talk), Dec. 2014, English, International conference

    Oral presentation

  • Structure from Motion for pointclouds creation from historicql imagery and UAV: Monitoring floodplain vegetation evolution in 3D

    GOMEZ ANDRE CHRISTOPHER, OBANAWA H, KATO A, HAYAKAWA Y, SAITO H

    5th Digital Earth Summit, Nov. 2014, English, Nagoya, Japan, International conference

    Oral presentation

  • Publishing International Scientific Papers in the field of geosciences: understanding the steps, mechanisms and pitfalls.

    GOMEZ ANDRE CHRISTOPHER

    Professional workshop at Universitas Gadja Madah, Nov. 2014, English, International conference

    Oral presentation

  • Glacier and Slope Formation Monitoring in New Zealand using UAV based imagery

    GOMEZ ANDRE CHRISTOPHER, PURDIE H

    5th Digital Earth Summit, Nov. 2014, English, Nagoya, Japan, International conference

    Oral presentation

  • Identifying flood disaster events using precipitation extreme indices over Northern Namibia

    PERSENDT F, ZAWAR-REZA P, GOMEZ ANDRE CHRISTOPHER

    Drivers, Scales and Context of Disaster Risk in the SADC Region,, Oct. 2014, English, Windhoek, Namibia, International conference

    Oral presentation

  • Glacier retreat. Feedbacks and implications for glacier tourism

    PURDIE H, GOMEZ ANDRE CHRISTOPHER, STEWART E, WILSON J, ESPINER S, BEALING P, KEY N

    IAG-NZGS Conference, Jun. 2014, English, Melbourne Australia, International conference

    Oral presentation

  • Coseismic Landslide Hazard Assessment using Geographic Information System

    SAPUTRA A, GOMEZ ANDRE CHRISTOPHER, HADMOKO D.S, SARTOHADI J

    Solo Indonesia, International Seminary on Geographic Information Systems, Jun. 2014, English, International conference

    Oral presentation

  • 3D Modelling of Inaccessible Areas using UAV-based Aerial Photography and Structure from Motion.

    OBANAWA H, HAYAKAWA Y, GOMEZ ANDRE CHRISTOPHER

    European Geophysical Union 2014, Apr. 2014, English, International conference

    Oral presentation

  • The Physical and Social Implications of Rapid Glacier Retreat: A case Study from Fox and Franz Joseph Glaciers, South Westland, New Zealand.

    PURDIE H, WILSON J, GOMEZ ANDRE CHRISTOPHER, STEWART E, ESPINER S

    SIRG international Conference, 2014, English, International conference

    Oral presentation

  • Remote Sensing from Space to the Ground for Environmental Monitoring.

    GOMEZ ANDRE CHRISTOPHER

    Universitas Muhammadyah Surakarta, 2014, English, International conference

    Oral presentation

  • Key-note Speech: High Resolution, High Frequency UAV-based remote sensing in Ecology, Environment and Earth Sciences: Development and data geoprocessing

    GOMEZ ANDRE CHRISTOPHER

    IEEE International Conference on Aerospace Electronics and Remote Sensing Technology (ICARES), 2014, English, International conference

    Oral presentation

  • Hazards, Risks and Disaster Mitigation in East Asia: the challenges around the corner.

    GOMEZ ANDRE CHRISTOPHER

    Hyogo University, 2014, English, Domestic conference

    Public discourse

  • Geology, Environment and Remote Sensing for Disaster Management.

    GOMEZ ANDRE CHRISTOPHER

    1st LAPAN International Conference (Keynote Speech), 2014, English, International conference

    Oral presentation

  • Assessing topographic control on sediment deposition patterns in coastal deposits

    KAIN C.L, GOMEZ ANDRE CHRISTOPHER, HART D.E, WASSMER P, GOFF J

    Earth Sciences Convention, 2014, English, New-Castle, Australia, International conference

    Oral presentation

  • 多摩川氾濫原における土地被服の変遷と地震の揺れの関係

    GOMEZ ANDRE CHRISTOPHER

    Tokyo University CSIS Days 2013, Dec. 2013, Japanese, Domestic conference

    Oral presentation

  • 地球表層かていに関わる新技術のしんぽと限界

    GOMEZ ANDRE CHRISTOPHER

    University of Niigata, Geology, Invited Lecture, Nov. 2013, English, Domestic conference

    Oral presentation

  • Clore-range remote sensing and GIS data processing: Progresses in Earth-Sciences and Potentialities in Forestry

    GOMEZ ANDRE CHRISTOPHER

    Hokkaido University, Guest Lecture, Oct. 2013, English, Domestic conference

    Oral presentation

  • Ground Penetrating Radar (GPR) Survey on Volcanogenic Outburst Flood Deposits, Northeastern Japan.

    Kataoka, K.S, GOMEZ ANDRE CHRISTOPHER

    Kagoshima, japan: IAVCEI 2013 – Forecasting Volcanic Activity, Jul. 2013, Japanese, International conference

    Oral presentation

  • Keynote Speech: Low-cost Remote Sensing and Crowd Sourced Data for Mass Movement, Hazards and Disasters in New Zealand

    GOMEZ ANDRE CHRISTOPHER

    Niigata, Japan: Disaster Prevention and Mitigation Symposium, April 20th 2013, Apr. 2013, English, International conference

    Oral presentation

  • Very Large 3D Dataset: Acquisition and GIS Processing

    GOMEZ ANDRE CHRISTOPHER

    Chiba University Faculty of Horticulture, 2013, English, Domestic conference

    Public discourse

  • Three dimensional reconstruction of paleotopography to assess the role of antecedent morphology before and after rapid deposition events.

    Kain, C, GOMEZ ANDRE CHRISTOPHER, Hart, D

    IAG, Paris, FRANCE, 2013, English, International conference

    Oral presentation

  • The influence of river configuration on inundation during high-energy coastal events

    Kain, C, GOMEZ ANDRE CHRISTOPHER, Hart, D

    IAG Australia, 2013, English, Perth, Australia, International conference

    Oral presentation

  • The Competent Professional Emergency Manager.

    Hurte, W, O'Steen B, GOMEZ ANDRE CHRISTOPHER

    Australian and New Zealand Disaster and Emergency Management Conference, 2013, English, International conference

    Oral presentation

  • SfM vs. RTK: Fight! (Structure from Motion versus Global Navigation Satellite System Real Time Kinetic

    GOMEZ ANDRE CHRISTOPHER, Starheim, C

    IAG, Paris FRANCE, 2013, English, International conference

    Oral presentation

  • Pyroclastic flow reworking and lahar triggering in the Kali Putih: Laboratory simulations and fieldwork observations

    Wassmer P, GOMEZ ANDRE CHRISTOPHER, Starheim C

    SEDIMER Workshop, 2013, English, Yogyakarta, Indonesia, International conference

    Oral presentation

  • Monitoring debris-flow deposit remobilization patterns with structure-from-motion (SfM) modelling.

    Starheim, C, GOMEZ ANDRE CHRISTOPHER, Hadmoko, S.D, Davies, T, Owens, T

    IAG Australia, 2013, English, Perth, Australia, International conference

    Oral presentation

  • Measurements of Trees Using Terrestrial Laser For Satellite Remote Sensing

    Kato, A, Morgenroth, J, Kelbe, D, GOMEZ ANDRE CHRISTOPHER

    IEEE International Geoscience and Remote Sensing Symposium, 2013, English, International conference

    Oral presentation

  • Graph Theory: the Ford and Fuklerson and the Edmonds-Karp Algorithms to Model Dynamic Sedimentary Systems.

    GOMEZ ANDRE CHRISTOPHER, Starheim, C, Hadmoko, D.S, Lavigne, F

    IAG, Paris, FRANCE, 2013, English, International conference

    Oral presentation

  • Generating high spatiotemporal resolution digital terrain models for debris flow deposits from 3D structure from motion imagery and an unmanned aerial vehicle.

    Starheim, C, GOMEZ ANDRE CHRISTOPHER, Davies, T, Owens, I, Hadmoko, D.S

    IAG, Paris, FRANCE, 2013, English, International conference

    Oral presentation

  • Exploring the intricacies of sub-surface debris-flow deposit architecture using a Ground Penetrating Radar system.

    Starheim, C, GOMEZ ANDRE CHRISTOPHER

    IAG Australia, 2013, English, Perth, Australia, International conference

    Oral presentation

  • Evacuation Routing Out of Tsunami Hazard Zones.

    SCHUSTER M, GOMEZ ANDRE CHRISTOPHER

    GI Forum 2013, Salzburg, Austria, 2013, English, International conference

    Oral presentation

  • Coastal Quakes: Using global datasets to expose an underrated hazard.

    Hart, D, GOMEZ ANDRE CHRISTOPHER, Bealing, P

    IAG, Paris, FRANCE, 2013, English, International conference

    Oral presentation

  • Assessing drainage network extractions in low-relief area from Lidar-derived DEM and DEMs derived from other data sources: a case study from the Cuvelai Basin, Namibia.

    Persendt, F, GOMEZ ANDRE CHRISTOPHER

    IAG, Paris, FRANCE, 2013, English, International conference

    Oral presentation

  • Scales in Environmental Sciences. University of Chiba

    GOMEZ ANDRE CHRISTOPHER

    Chiba Universitt - Guest Lecture CERES, Jan. 2013, English, Domestic conference

    Public discourse

  • Close-range ‘remote-sensing’: Combining techniques to relate sediment deposits to processes

    GOMEZ ANDRE CHRISTOPHER

    University of Chiba, Centre for Environmental Remote Sensing: Yube Seminar Series, Dec. 2012, English, Domestic conference

    Oral presentation

  • The worst day since the WWII capitulation of Japan

    GOMEZ ANDRE CHRISTOPHER

    Seminar at University of Gadjah Mada, Yogyakarta, Indonesia, Nov. 2012, English, International conference

    Public discourse

  • Linking deposits and forms to processes: Geospatial Sciences to tackle Erosion Issues.

    GOMEZ ANDRE CHRISTOPHER

    Department of Agriculture, University of Kyoto, Japan - invited Seminar, Nov. 2012, English, Domestic conference

    Public discourse

  • Automated 3D-RGB Topology of SfM-MVS Derived Data for Environmental Analysis: Application to the Kali Putih River, Merapi Volcano

    GOMEZ ANDRE CHRISTOPHER

    IGI International Seminar: Utilization of Geospatial Information to Raise Environmental Awareness in Realizing the Nation Character, Nov. 2012, Domestic conference

    Invited oral presentation

  • Smashing children hearts on concrete and hanging engineers: The 11 March 2011 tsunami.

    GOMEZ ANDRE CHRISTOPHER

    Meeting of the New Zealand Geographical Society, 2012, English, International conference

    Oral presentation

  • Large-scale internal structure in volcanogenic breakout flood deposits: Extensive GPR survey on volcaniclastic deposits

    Kataoka, K, GOMEZ ANDRE CHRISTOPHER

    American Geophysical Union Fall Meeting, 2012, English, International conference

    Oral presentation

  • Impacts of tsunami on Banks Peninsula: Sedimentary signatures of previous events.

    Kain, C, GOMEZ ANDRE CHRISTOPHER, Hart, D.E

    New Zealand Coastal Society Annual Conference, 2012, English, International conference

    Oral presentation

  • How Hazard Planners Created the Tohoku Catastrophe

    GOMEZ ANDRE CHRISTOPHER, Hart, D.E

    6th Australasian Natural Hazards Management Conference, 2012, English, International conference

    Oral presentation

  • Flood hazard mapping using multisensory multispectral satellite data fusion in the Cuvelai basin, Namibia

    Persendt, F, GOMEZ ANDRE CHRISTOPHER

    16th SANCIAHS National Hydrology Symposium, 2012, English, International conference

    Oral presentation

  • Earth Quakes – Coastal and River Disasters. Christchurch

    Hart, D, GOMEZ ANDRE CHRISTOPHER, Kelland, E, Wassmer, P

    Australasian Hazards Conference, 2012, English, International conference

    Oral presentation

  • Combining SfM and GIS to efficiently monitor landform change. Surakarta City, Java, Indonesia

    Starheim, C, GOMEZ ANDRE CHRISTOPHER, Hadmoko, D.S

    IGI International Seminar: Utilisation of geospatial information to raise environmental awareness in realizing the nation character, 2012, English, International conference

    Oral presentation

  • Coastal quakes: New Zealand’s underrated hazard complex. Auckland, New Zealand

    Hart, D, GOMEZ ANDRE CHRISTOPHER, Kirk, R.M, Hughes, M.W, Kelland, E, Wood, G.B, Davis, B, Giovinazzi, S

    New Zealand Coastal Society Annual Conference (NZCS), 2012, English, International conference

    Oral presentation

  • Christchurch’s Coastal and River Quakes: Implications for disaster resilience in New Zealand. Christchurch, New Zealand

    Hart, D, GOMEZ ANDRE CHRISTOPHER, Kelland, E

    University of Canterbury Earthquake Research Forum, 2012, English, International conference

    Oral presentation

  • Characterizing in-flow sediment dynamics of lahars affecting Mount Semeru, Indonesia.

    Starheim, C, GOMEZ ANDRE CHRISTOPHER, Davies, T, Lavigne, F, Wassmer, P

    6th Australasian Natural Hazards Management Conference, 2012, English, International conference

    Oral presentation

  • Volcaniclastic Sedimentation Process in Java, Indonesia. Guest Speaker at the Department of Geology & Research Institute for Natural Hazards and Disaster Recovery

    GOMEZ ANDRE CHRISTOPHER

    Niigata University, Dec. 2011, English, International conference

    Invited oral presentation

  • Understanding the Tsunami of December 26th, 2004 in Banda Aceh: Event, Impacts and Post-tsunami Campaign

    GOMEZ ANDRE CHRISTOPHER

    University of Canterbury, Geology Department Seminar, Aug. 2011, English, Domestic conference

    Public discourse

  • Application of Computer Vision to Lahar Automatic Detection

    GOMEZ ANDRE CHRISTOPHER

    Conférence Nationale Des Jeunes Géomorphologues organisée par le G.F.G., Feb. 2010, English, Domestic conference

    Oral presentation

  • Geostatistic Analysis of Blocks Distribution Detected by Remote Sensing: Case Study in the Curah Lengkong Valley, Semeru Volcano, Indonesia

    GOMEZ ANDRE CHRISTOPHER

    Conference Nationale des Jeunes Geomorphologues GFG, 2010, French, Domestic conference

    Oral presentation

  • The 2004 tsunami in Banda Aceh, an overview

    GOMEZ ANDRE CHRISTOPHER

    guest speaker at Veteran Universitas in Jogjakarta Indonesia, 2006, Domestic conference

    Oral presentation

  • Ground Penetrating Radar Imaging of Pro-glacial Landforms in the Upper Waimakariri River (New Zealand)

    Christopher GOMEZ, Heather PURDIE, Justin HARRISON, Paul BEALING, Nicholas KEY

    Japanese Geophysical Union and American Geophysical Union Joint Meeting, 12 Jul. 2020

  • A new method to measure in situ soil density using SfM-MVS photogrammetry

    Christopher GOMEZ

    Japanese Geophysical Union and American Geophysical Union Joint Meeting, 12 Jul. 2020, English