Christopher Gomez

Kobe University | Shindai · Graduate School of Maritime Sciences

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 t...

The economic downturn at the start of the 21st Century combined with the rise of new economies have helped propelling the need for cheaper, rapid and yet accurate data acquisition methods, including point-cloud producing technologies. As population is ageing in countries like Japan or Taiwan, and as climate change is bound to increase the frequency...

Rainfall-triggered volcanic debris flows (VDFs), or lahars, frequently occur during and/or immediately after eruptions, often because of decreases in the infiltration capacity resulting from the deposition of fine volcanic materials. Although the infiltration capacity recovers and the frequency of VDFs decreases within a decade, VDFs have continued...

We propose a vast area in the middle of Lombok, Indonesia, dominated by hummock hills, is a debris avalanche deposit (DAD). We define this > 500 km2 area as Kalibabak DAD that may originate from Samalas volcano. No descriptions of the morphology, stratigraphy, mechanism, and age of this DAD have yet been reported; this contribution bridges this res...

The radon (Rn) and thoron (Tn) concentrations and other environmental parameters were measured in the vicinity of active faults in two regions with different geology structure of Japan. The range of measured values was from 1.2 to 74 kBq m$^{-3}$, 1.1 to 38.9 kBq m$^{-3}$, 0% to 4.35%, and 2$\times $10$^{-13}$ to 4$\times $10$^{-11}$ m$^{2}$, for R...

Citation: Yousefi, S.; Emami, S.N.; Nekoeimehr, M.; Rahmati, O.; Imaizumi, F.; Gomez, C.; Valjarevic, A. Abstract: Forest roads have been recognized as one of the significant contributors to soil erosion processes in forested areas. The construction and maintenance of forest roads can cause severe environmental impacts, including soil erosion, sedi...

Gully erosion presents an environmental challenge in many arid landscapes, exerting profound effects on land stability, agricultural viability, and ecological equilibrium. Despite its importance, empirical data are limited due to the rarity of extreme hydrological events. To address this data gap, our study provides a comprehensive analysis of the...

This study assessed the geogenic radon potential using PECAME, an innovative tool designed to simultaneously measure soil permeability and CO2 concentration -- two key parameters for understanding radon transport in soil. Comparative field studies using the RADON-JOK device in various geological settings in Japan and Poland demonstrate the effectiv...

Purpose The ineffectiveness of flood control in climate-impacted majority-world cities like Jakarta highlights the need for policies that integrate local knowledge and embrace water harmony rather than resistance. This study explores flood adaptation in North Jakarta's kampungs (urban informal settlements), aiming to enhance the efficacy of current...

River ecosystem services (RES) are vulnerable to landscape changes mainly by volcanic eruptions. Therefore, this study aims to assess RES in the volcanic area which was affected by the major and minor eruptions of Mount Merapi, Indonesia. The RES referred to the regulating and supporting services of the Krasak River in Jogjakarta. The research invo...

As a Mw 8.0 Nankai Trough Earthquake is predicted with an 80% probability of occurrence within the next 30 years, the efficiency of check dams in the mountains above Kobe City is a crucial question when considering co-seismic landslide disaster risk management. In the present contribution the author aimed to define which subsection of the Sumiyoshi...

As climate change creeps into the 21st century, the intensity of debris flows due to heavy and concentrated rainfall has increased in mountainous regions of Japan and East Asia. However, the relationship between climate change and an increase in debris flows is likely to be non-linear. Rainwater infiltrates more quickly into porous material, and th...

In the aftermath of the heavy rainfall events of 2017 in North Kyushu, Asakura (Japan), driftwood-related disaster risk has proven to be as real as it was in 1933, when wood-laden debris-flow invaded the city centre of Kobe City near Sannomiya station. Despite a temporary truce obtained thanks to extensive Sabo dam constructions, climate change, th...

Lava domes created by volcanoes often cause pyroclastic and debris flows, which have a significant impact on the surrounding infrastructure and population and have been the subject of much research. However, because volcanic domes tend not to survive the eruptions that form them, the instability of domes that survive eruptions such as Unzen Fugenda...

On 13th August 2021 at Unzen Volcano (Japan), an 81 mm.hr-1 peak-rainfall (1486 mm in 2 weeks) triggered series of erosion and deposition features in the Tansandani and the Gokurakudani gullies, all adding up to 57,800 m ³ of erosion and 39,600 m ³ of deposition. Upstream of the Sabo dam located at the exit of the Tansandani Gully, a large deposit...

Water resources have become crucial for livelihood in the previous decade [1,2]. Population pressure, climate change, hydrological disasters, and inadequate implementation of integrated water resource management have all been topics of concern among water resource professionals [3,4,5]. Meanwhile, poor hydrological data and a lack of government pol...

On the first day of 2024, a strong Mw.7.6 earthquake followed by a tsunami shook the Noto Peninsula (Japan) located on the coast facing the Sea of Japan. It resulted in numerous casualties, infrastructures and dwelling destroyed. The earthquake also triggered at least 930 coastal and mountain co-seismic landslides that were digitized from the emerg...

Soil erosion is a major environmental problem with severe ecological and socioeconomic consequences. Monitoring water erosion is considered one of the most significant issues in land management. There are two current approaches for collecting data in soil erosion monitoring. The first approach is based on manual data collection that is slow and pro...

In this article, desertification and dune progression over vegetation was quantified using remote sensing data. However, vegetation buried under sand blowout could not be counted using this method. Therefore, to estimate the extent of buried vegetation, a GPR campaign was conducted over the coastal sand-dune of Tottori Prefecture (Japan) in combina...

As a Mw 8.0 Nankai Trough Earthquake is predicted with an 80% probability of occurrence within the next 30 years, the efficiency of check dams in the mountains above Kobe City is a crucial question when considering co-seismic landslide disaster risk management. In the present contribution the author aimed to define which subsection of the Sumiyoshi...

A special issue of Land (ISSN 2073-445X) entitled "Remote Sensing Application in Landslide Detection and Assessment". This special issue belongs to the section "Land Innovations – Data and Machine Learning". Deadline for manuscript submissions: 31 December 2023. More information at: https://www.mdpi.com/journal/land/special_issues/XYS26JXR2Z

On 5–6 July 2017, an unstable atmospheric condition caused an unusual concentration of rainfall above the Northern part of Kyushu Island, triggering a set of hydro-meteorological hazards. Within the affected area, the mountainous subwatershed of the Akatani River was significantly impacted by numerous landslides combined with debris flow and floods...

More and more attention is devoted to the icy moons of the Solar System, including Europa, the second Galilean satellite of Jupiter, since the discovery of potential liquid water and the possibility of extra-terrestrial life harbored in its subsurface ocean below its icy crust. Along with the renaissance of the study of icy satellites, the ongoing...

Forest roads have been recognized as one of the significant contributors to soil erosion processes in forested areas. The construction and maintenance of forest roads can cause severe environmental impacts, including soil erosion, sedimentation, and degradation of aquatic ecosystems. In summary, this study contributes to our understanding of the im...

The study introduces a theory about an Evander-size impact on the surface of Dione. Our study suspects a relatively low-velocity (≤5 km/s) collision between a ca. 50-80 km diameter object and Dione, which might have resulted in the resurfacing of one of the satellite's intermediate cratered terrains in various ways, such as surface planing by "plow...

Hillslope and mountain roads are often the source of erosion, which in turn can lead to larger landslides and other types of mass-movements. For this reason, low-cost repeat surveys that can be done by practitioners and not solely scientists and engineers is essential. To solve this issue the present contribution shows the testing and applicability...

The study introduces a theory about a giant impact on the surface of Dione. Our study suspects a relatively low-velocity (≤5 km/s) collision between a c.a. 50–80 km diameter object and Dione, which might have resulted in the resurfacing of its intermediate cratered terrain. The source of the impactor might have been a unique satellite-centric debri...

Wispy Terrain, with its chasmata, is one of the enigmatic regions of Dione. It consists of quasi-parallel graben, and troughs, in parts with horsts, indicating extensional and shear stresses. This study introduces some observations of compression-related features and proposes a new regional formation model. The study of the relationship between imp...

The first images of Jupiter's moon Europa from the Voyager missions sparked the curiosity about the lineament system appearing at the surface. Curiosity quickly turned into profound interest, following the discovery of its subsurface ocean, which may harbour life below the thick ice crust. This study revisits Europa and reinvestigates its surface u...

In the last decade, rainfall radar has been deployed at volcanoes like Mt. Merapi in Indo-nesia, and can even cover a whole country like in Japan, where the X-Rain (eXtended Radar Information network) product has been available for local research. However, the linkage between rain-gage data and radar spatial data (over a 250 m x 250 m grid) still p...

Volcanic gullies develop U-shape cross-profiles due to the lahars that shape them after eruptive events. Over time, the processes of sediment-transfer change and the erosion of sub-vertical walls become a leading process. It results in debris-cones at their foot. However, the processes that generate these landforms is still unclear. Indeed, the sur...

Desertification and dune progression over vegetation is quantified using remote sensing data, but vegetation, eventually temporarily, buried under sand blowout may escape such assessment, and to estimate the extent of buried vegetation, a GPR campaign was conducted over the coastal sand-dune of Tottori Prefecture (Japan) in combination with a high-...

Landslides are natural hazards that can cause catastrophic life losses and damage to infrastructures and communities. In Iran, landslide exposure has been predominantly increasing in the Zagros Mountains, notably along the lifelines, such as road networks. Therefore, this study aimed to investigate the landslide vulnerability of a 6682 km road netw...

Spatial approaches, based on the deformation measurement of volcanic domes and crater rims, is key in evaluating the activity of a volcano, such as Merapi Volcano, where associated disaster risk regularly takes lives. Within this framework, this study aims to detect localized topographic change in the summit area that has occurred concomitantly wit...

This chapter turns towards a specific type of hillslopes: volcanoes and how pointclouds can be used in volcanic geomorphology. The chapter first presents general features of volcanic geomorphology, before presenting the use of SfM-MVS and LiDAR to deal with the specific difficulties of working in volcanic environment (i.e. recording steep craters’...

This chapter continues the progression upstream, and it then presents the use of pointcloud technologies for hillslopes. The chapter starts with a short overview of some of the slope processes and their numerical expression and how those concepts can be used for the application of geomorphology to hazard management. The chapter then presents a set...

River wood-debris are a major hazard to lives and infrastructures, because tons of wood material can travel nearing the speed of the flood-flow. If post-event mapping, detection and numerical simulation have made important progress, it is still impossible to detect the wood-debris as they travel, due to poor visibility conditions (rain, night…). Th...

Landscape is very dynamic [1,2,3]. In line with the development of an increasingly climate change [4] and high population, the dynamics of the landscape have also changed due to an increase in the intensity of the population in utilizing land. The condition of the corona virus pandemic since the beginning of 2020 has resulted in two impacts to the...

The first chapter is an introduction to the book. It explains what is meant by pointcloud through the manuscript as well as how the technology has emerged through the field of geomorphology. Within this framework, the laser and photogrammetric technologies (airborne laser scanner, terrestrial laser scanner and structure from motion multiple view st...

This chapter starts with a presentation of the common pointcloud formats used in geomorphology and civil engineering, as well as a rapid presentation of three freeware and software (with free academic licence) available to read and process pointcloud data. The chapter then explains the registration process of pointclouds and the classification of p...

The last chapter builds on the previous 6 chapters, which are more technical, to propose a reflection of what it means for the geomorphologist to work with high-resolution pointcloud technology. First, the chapter explains that values such as sediment density and compaction, which could be safely ignored in the past are now having an increasing imp...

The second chapter presents the generation process of pointcloud in geomorphology. The chapter starts with laser technologies that have given rise to aerial laser scanner (ALS) and terrestrial laser scanners (TLS) and how they have emerged in geomorphology, notably through the needs in fluvial geomorphology to detect minute topographic changes, and...

This chapter starts the section of applications of pointcloud technologies in geomorphology, and as this section starts at the shore, going up the mountain. This chapter presents the advantages and difficulties of working and collecting pointclouds in coastal and floodplain areas. The chapter starts with some very basic ideas on river catchments, s...

Spatial approach based on the deformation measurement of volcanic dome and crater rim is key to evaluate the activity of a volcano, such as Merapi volcano where associated disaster risk is regularly taking lives. Within this framework, this study aime to detect localized deformation and change in the summit area that has occurred concomitantly with...

This work aims to introduce and test various semiquantitative field methods and environmental magnetic measurements to help prepare future planetary missions on Mars. For analog observations, paleosols of loess successions in various stages of soil development were investigated and were used as models to infer environmental change during environmen...

Increasing attention has been paid to multi-hazards in environmental disaster studies produced during the last decade. Multi-hazard studies focus on the occurrence, interaction and effect of several natural hazards in the same region. Despite the increasing number of multi-hazard studies, few investigations have focused on global-scale multi-hazard...

The text offers a comprehensive and unique perspective on disaster risk associated with natural hazards. It covers a wide range of topics, reflecting the most recent debates but also older and pioneering discussions in the academic field of disaster studies as well as in the policy and practical areas of disaster risk reduction. This book will be o...

Debris-flows are recurrent events on mountain- and hill- slopes, and they have been the object of numerous field investigations and sampling, however most of this work reposes on imagery and outcrop analysis, in such a way that there are still only a handful of studies investigating the internal architecture of these events’ deposits. In the presen...

Land use/cover (LU/LC) classification provides proxies of the natural and social processes related to urban development, providing stakeholders with crucial information. Remotely sensed images combined with supervised classification are common to define land use, but high-performance classifiers remain difficult to achieve, due to the presence of m...

More and more attention has been raising toward the icy moons of the Solar System since the discovery of their potential liquid water [1], and the astrobiology potential below their surface ice [2]. In addition, the ongoing preparation of JUICE (JUpiter ICy moons Explorer) mission is boosting the research as well. Before the hopefully successful JU...

GPR investigation of subsurface cracks above a fault in Kumamoto prefecture

Ground Penetrating Radar Investigation of Seismic cracks in agriculture terrace

More and more attention has been raising toward the icy moons of the Solar System since the discovery of their potential liquid water, and the astrobiology potential below their surface ice. In addition, the ongoing preparation of JUICE (JUpiter ICy moons Explorer) mission from ESA is boosting the research as well. One of the many research topics,...

Internal temperature variations of pyroclastic flows and their deposits are arguably the most challenging data to acquire. As a preliminary study of the temperature variation inside pyroclastic flows, the remains of Onokoba Elementary School (Shimabara, Japan) were investigated. The elementary school is located in the close vicinity of Unzen volcan...

The pre-colonial history (i.e. before the 16th century) of Tonga and West Polynesia still suffers from major gaps despite significant scientific advances in recent years, particularly in the field of archaeology. By the 14th century, the powerful Tu’i Tonga kingdom united the islands of the Tongan archipelago under a centralised authority and, acco...

In the aftermath of pyroclastic density current-dominated eruptions, lahars are the main geomorphic agent, but at the decadal scale, different sets of processes take place in the volcanic sediment cascade. At Unzen volcano, in the Gokurakudani gully, we investigated the geomorphologic evolution and how the topographic change and the sediment change...

Poor understanding of the differential evolution of interglacial climate over various regions in Eurasia greatly limits our ability to predict the specific local impacts of future climate change. Here we demonstrate starkly opposing trends in interglacial intensities in Asia and Europe over the early Middle Pleistocene and Mid-Brunhes Transitions b...

In the aftermath of pyroclastic-flow –dominated eruptions, lahars are the main geomorphic agent, but at the decadal scale, different sets of processes take place in the volcanic sediment cascade. At Unzen Volcano, in the Gokurakudani Gully we investigated the geomorphologic evolution and how the topographic change and the sediment change over time...