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…). The present work aims to solve this issue by adapting Ground Penetrating Radar as an electromagnetic imaging method for in-flow wood debris detection. Laboratory test over a water circulation flume using a 800 MHz nominal frequency antenna sampling at 100 Hz a set of single wood logs of 20 cm length has shown that the method had the potential to detect moving wood debris, and that it could “see” underneath to the flume floor. The experiments resulted in the ability to count wood debris travelling underneath the antenna, and instantaneous velocity were obtained with velocities ranging from 0.307 to 0.352 m/s, which slightly higher than the averaged velocity measured from video, due to the acceleration time when wood was introduced in the flume.

Since its last eruption from 1990-1995, Unzen Volcano (Shimabara Peninsula, Japan) has been quiescent since. At its summit a complex Dacitic dome that expanded towards the East, in the direction of the Mizunashigawa-valley has grown during the eruption onto previously deposited volcanoclastic sediments. As a small portion of the domes have generated rockfalls and as the surrounding gullies have been eroding headwards, the stability of the dome and its evolution is essential for hazards and disaster-risk monitoring and for understanding the decadal-scale volcanic geomorphological change occurring in between eruptions. Therefore, the present contribution aims to (1) quantify the dome movement and (2) separate the different parts of the dome to understand how it deforms; and (3) what is the link between rainfalls and the dome movement. The method relies on the Unzen GbSar system (Ground Based radar interferometry system) and on hourly rainfalls from raingage stations at Unzen Volcano. As a result, the authors have identified that (1) the lower part of the dome rises and falls more rapidly than the upper part of the dome when rainfall is less than 100 mm/48 hours, and (2) the upper and lower parts of the dome move up and down at the same level when rainfall exceeds 100 mm/48 hours. In turn, when rainfall exceeds 250 mm/48 hours, then the upper part of the dome also displays further downward movement, so that the entire dome might be moving down like an accordion.

This study compares the results of analyzing tsunami simulations that are based on two approaches of characterizing earthquake slips, i.e., uniform (simplistic) and heterogeneous (complex) distributions. The aim of this study is to compare how heterogeneous and uniform distributed data affect the classification of tsunami maximum near-shore tsunami amplitudes. Due to the lack of historical earthquake and tsunami data to train the forecasting model, 4000 stochastic tsunami simulations are employed. The focused location is Iwanuma, Japan, where ocean bottom sensors (OBS) S-net network has been deployed. Multiple linear regression combined with Akaike Information Criterion (AIC) is applied to the simulated off-shore wave amplitude data to fit the model. The estimated tsunami amplitude is classified into four levels of warning classes. The performance of the models is quantified by the accuracy of the confusion matrices and is compared with the base model that only uses earthquake information. The forecasting accuracy can be improved by 30% when the wave amplitude data are used as additional information. The heterogeneous slip-based model reaches a higher accuracy than the uniform-slip based model. The result of this study is particularly valuable for setting up an OBS-based system for monitoring the physical phenomena of tsunamis and choosing heterogeneous as a preferable slip distribution when tsunami events are simulated.

Recent landslides in Mbonjo, located between 3°55’’–4°13’’N and 9°12’’–9°23’’E in
the coastal town of Limbe were mapped using an unmanned aerial vehicle, field mapping
and remote sensing techniques and documented in this paper. This town is susceptible to
natural hazards and in July 2018 and 2020, a swarm of landslides occurred in Mbonjo
towards the outskirt of Limbe, killing five people and injuring 10 others, obstructing the
road and destroying important properties. These landslides were studied for a better un-
derstanding and the occurrence of such natural phenomena and human threat diminution.
From the field studies, the slides were small to medium scale, characterized by low slope
gradients (15-250), short depletion zones (20-25m) and length (~31.1m). These slides cov-
ered an area of 603.5-2000.75m2 and the volume of ground debris were bracketed between
626.81 and 8757.60m3. Slope steepness and human activities such as excavation of the
slopes were the main conditioning factors, whereas intense rainfall was the main trigger
of Mbonjo landslides. It is urgent to take concrete measures to tackle this serious threat to
human life in the study area.

This work re-examines the salt unit through the Kribi-Campo Sub-basin on the southeast part of the Cameroon Atlantic Margin. The results obtained from borehole data analysis show the occurrence of evaporitic unit, localized in the Kribi area. The well to seismic-tie analysis reveals that this unit is observed beneath the Top Albian Unconformity and between the Flooding and Maximum Flooding Surfaces. Two characters of salt dome and salt strips are described. Their depositional context seems to be related to a significant sea-level drop induced by a margin uplift during the Aptian. Concerning the petroleum implications, the target units constitute good potential of stratigraphic traps in the study area, due to the observation of flatspot indicators.

The relict (palimpsest and lowstand) deposits of the Cilento continental shelf have been analyzed based on the geological interpretation of subsurface Chirp sections, calibrated with core data. A progradational unit, overlying the acoustic basement, is interpreted as the beach deposits of the isotopic stages 4 and 5. This unit is overlain by a seismo-stratigraphic unit, composed of coarse-grained organogenic sands and interpreted as relict sands. This unit consists of sandy ridges, occurring at water depths ranging between 130 and 140 m and has been interpreted as submerged beach deposits, genetically related with the marine isotopic stage 2 (Last Glacial Maximum; starting date 29 ky B.P.) .

Lagoon ecosystems represent the most vulnerable ecosystems, often subject to multiple anthropogenic pressures, including numerous disturbances in terms of hydro-sedimentary dynamics. The lagoon of Moualy Bouselham, also known as "Merja Zerga", located on the Atlantic coast of Morocco. This lagoon was included in the RAMSAR list of wetlands on June 20, 1980. It hosts several important human activities including fishing. Nevertheless, the growth of urbanization and the development of economic activities, including the overexploitation of natural resources (fishing, agriculture), continuously lead to serious changes in the physical, chemical and biological state of the lagoon. These changes include, mainly, water and sediment pollution by heavy metals, closure of the main entrance inlet, loss of biodiversity, and, consequently, a decrease in the availability of ecosystem services (ES). Today, the lagoon suffers from a growing containment problem due to the significant increase in the amount of sediment, especially in the entrance zone, which leads to the accumulation of sand and the creation of sandy areas called "sandpits". This situation presents a risk of closure of the inlet, leading to further environmental degradation and economic problems. Aware of the magnitude of this problem, the decision makers proposed a study to reduce sand deposits by suggesting the most practical options in terms of hydrodynamic improvements inside the lagoon. In this sense, this study focuses on the relationships between socioeconomic factors and their impacts on the lagoon environment. To this end, a DPSIR approach is used, describing the causal links between "driving forces" (economic sectors, human activities), "pressures" (emissions, wastes), "states" (physical, chemical, and biological), and "impacts" on ecosystems, human health, and functions, ultimately leading to policy "responses" (prioritization, target setting, indicators). Likewise, some management proposals were discussed in this study, taking into account the current state of the lagoon as well as the ecological sustainability and well-being of the local population. On the other hand, this work focuses on hydro-sedimentary modeling using the numerical model Mike 21 to assess the hydrodynamic balance of Moulay Bouselham lagoon in order to participate in the management of this ecosystem to maintain its sustainability and protect natural resources.

Shallow landslides which are generally triggered by extreme precipitation events are increasingly becoming common in the world. Societies have had difficulty in keeping up with the exponentially rising shallow landslides in recent years. Despite considerable progress in engineering studies, shallow landslides continue to cause much damage in different areas of the planet. Therefore, runout analyses are becoming more and more popular in an attempt to resilience the negative effects of shallow landslides. Runout analyses are such crucial parts of shallow landslide studies that researchers have been keen on contributing to the existing knowledge. Earlier research suggested that runout analyses can be studied with empirical-statistical and numerical methods. Although there exist numerous landslide runout studies related to empirical-statistical and numerical solutions, it is not yet encountered a comparison of empirical-statistical and numerical methods' advantages and disadvantages in the literature. This research presents an evaluation of the advantages and disadvantages of the runout analysis methods.

The Oualidia lagoon (Morocco) is a RAMSAR site due to its importance as an essential paralic ecosystem for migratory birds. In the late 2000s, this environment suffered from a silting up of its channel which caused a confinement and a total or partial suspension of some ecosystem services. In 2011, after a study of the hydrodynamics of the lagoon, a sediment trap system was created to remedy the silting of the lagoon.

In this study, we investigate the actual hydrodynamic behavior of the lagoon after 10 years of the creation of the sediment trap, using a 2D hydrodynamic model to analyze and monitor the lagoon hydrodynamic. We created a numerical grid using updated bathymetric data that was collected in April 2021 and covers the entire lagoon and a large part of the open ocean. Using this grid, we ran the model over a period of one month, from 1^st to 30^th April 2021, to cover all tidal frequencies, using a time step of 10 minutes. This period was chosen to correspond to the period of in situ measurements (using ADCP equipment) in order to be able to compare the measured and simulated outputs. The hydrodynamic circulation of the lagoon was simulated taking into account different forces such as tides and winds. As a result, the final model outputs are in agreement with the measured data. The simulation with water level and winds produced current values closest to those measured at three different stations inside the lagoon. The comparison of a state of progress from 2011 to 2021 showed a slow but successful role of the sediment trap.

The Southern Ocean waters exchange freshwater, nutrients, carbon, heat, and salt to the Equator and influence the global carbon budget. Therefore, it is essential to understand the variations in Southern Ocean circulation during the last deglacial period to comprehend its changes with climate change. This modeling study employs a fully coupled Earth system model to investigate the Southern Ocean Subantarctic Mode and Antarctic Intermediate Waters distribution during the last deglaciation. The simulation shows that the Southern Hemisphere’s low-level winds overlap with the zone of maximum mixed layer depth, signifying the impact of westerlies in the Southern Ocean waters. The results indicate that the Southern Ocean Subantarctic Mode and Antarctic Intermediate Waters are fresher, warmer, and about 2.4 times deeper during the early Holocene compared to the Heinrich-1. The simulated Antarctic sea ice boundary (ocean surface area covered with more than five percent sea ice fraction) overlaps with the poleward edge of the Antarctic Intermediate Waters, and the Southern Ocean mixed layers. Additionally, the simulated quasi-permanent sea ice boundary (ocean surface area covered with more than eighty percent sea ice fraction) and the zone of Subantarctic Mode and Antarctic Intermediate Waters shifted polewards by about 5° and 10°, respectively, during the early Holocene compared to the Heinrich-1. Therefore, our study highlights a close link between the Antarctic sea ice distribution and the Southern Ocean Subantarctic Mode and Antarctic Intermediate Waters during the last deglacial period.