GeoHazards, Volume 6, Issue 1 (March 2025) – 15 articles

Debris flows are one of the most common and frequent natural hazards in mountainous environments. For this reason, there is a need to develop monitoring systems aimed at better understanding the initiation and propagation mechanisms of these phenomena to subsequently adopt the most reliable mitigation measures to safeguard anthropic assets and human lives exposed to the impact of debris flows in alluvial fan areas. However, the design of a responsive monitoring system cannot overlook the need for a thorough understanding of the catchment in which debris flows occur. This knowledge is essential for making optimized decisions regarding the type and number of sensors to include in the monitoring system and ensuring their accurate and efficient placement. In this paper, it is described how the preliminary characterization of an Alpine catchment and the geo-hydrological processes that have historically affected it—such as the lithological and geomechanical classification of the catchment’s bedrock, the identification and description of sediment source areas, the characterization of debris flow occurrence and quantification of the triggering causes—contribute to the optimal design of a monitoring system. Additionally, the data recorded from the sensors during a debris flow event in summer 2024 validate and confirm the results obtained from previous research. Full article

Slope failure, as a natural disaster, can cause extensive human suffering and financial losses worldwide. This paper introduces a new soil moisture extended cohesive damage element (SMECDE) method to predict railway slope failure under heavy rainfall. A correlation between rainfall intensity and soil moisture content is first established to create an equivalence between the two. Considering slope failure mechanisms dominated by the loss of soil or the cohesion of slope materials due to heavy rainfall infiltration, the soil moisture decohesion model (SMDM) is developed using previous experimental data to express how soil cohesion varies with different soil moistures and depths. The SMDM is incorporated into the extended cohesive damage element (ECDE) method to fundamentally study slope failure mechanisms under varying soil moisture levels and depths. The proposed SMECDE approach is used to predict the failure propagation of a selected railway embankment slope at the critical soil moisture or rainfall intensity. This SMECDE failure prediction is validated using relevant data from previous fieldwork and meteorological reports on the critical rainfall intensity at the site. Additionally, the corresponding slope damage scale prediction is validated with a large plastic deformation analysis using the commercial FEM package ABAQUS. Full article

In 2011, a M 5.7, earthquake struck near Mineral, Virginia, about 130 km southwest of Washington, D.C., prompting studies on paleoliquefaction to better understand the earthquake potential of the Central Virginia seismic zone and the hazard it poses to the Mid-Atlantic region. Researchers identified earthquake-induced liquefaction features along the Appomattox and Rapidan rivers, dated sediment and estimated the ages of these liquefaction features as well as features previously found along several other rivers in the seismic zone, and evaluated scenario earthquakes to constrain the locations and magnitudes of past earthquakes. Evidence suggests that historical earthquakes (M 5.25–5.5) in 1758, 1774, and 1875 C.E. caused liquefaction along the Appomattox, James, and Pamunkey Rivers, and a paleoearthquake (M 6.5–6.75) around 2640 ± 80 yr B.P. near Wyndham Forest caused liquefaction along the Appomattox River and across the seismic zone. Similarly, an earthquake (M 5.5–5.75) around 1690 ± 50 yr C.E. may have triggered liquefaction along the Rapidan River. Full article

This systematic literature review aims to review studies on post-wildfire landslides. A thorough search of Web of Science, Scopus, and other online library sources identified 1580 research publications from 2003 to 2024. Following PRISMA protocols, 75 publications met the inclusion criteria. The analysis revealed a growing interest in research trends over the past two decades, with most publications being from 2021 to 2024. This study is divided into categories: (1) systematic review methods, (2) geographical distributions and research trends, and (3) the exploitation of post-wildfire landslides in terms of susceptibility mapping, monitoring, mitigation, modeling, and stability studies. The review revealed that post-wildfire landslides are primarily found in terrains that have experienced wildfires or bushfires and immediately occur after rainfall or a rainstorm—primarily within 1–5 years—which can lead to multiple forms of destruction, including the loss of life and infrastructure. Advanced technologies, including high-resolution remote sensing and machine learning models, have been used to map and monitor post-wildfire landslides, providing some mitigation strategies to prevent landslide risks in areas affected by wildfires. The review highlights the future research prospects for post-wildfire landslides. The outcome of this review is expected to enhance our understanding of the existing information. Full article

Increases in flood magnitude due to climate change increase the necessity of resilient river levees to prevent the breaching that can contribute to reduced flood inundation volume even when overtopping from a levee occurs. When a levee is composed of cohesive soil and the levee crest is paved, overtopping can lead to a waterfall-like nappe flow due to the erosion of the downstream slope of a levee. This flow subsequently expands the scour hole and increases the risk of levee failure. Although some models of scour hole expansion due to nappe flow were proposed, flow structures in the scour hole were not adequately taken into account. This study aimed to clarify the flow structure, including formation of vortices in the scour hole, by conducting flow visualization experiments and three-dimensional numerical analyses. After clarifying the flow structure, this study proposed a simplified model to calculate the bottom shear stress in a scour hole on the levee side. The accuracy of the estimated bottom shear stress was verified by comparing the results with a three-dimensional numerical analysis. This proposed method can predict further erosion of a scour hole. Full article

Urban development and climate change are two main impacting factors in the thermal environment of cities. This study aims to analyze future changes in Mean Radiant Temperature (MRT), one of the main contributors to human thermal comfort and the concept of Urban Heat Island (UHI), considering climate change and urban development scenarios in the study area, Fredericton, New Brunswick, by 2050. The analysis utilizes the SOLWEIG (Solar and Longwave Environmental Irradiance Geometry) model from the Urban Multi-scale Environmental Predictor (UMEP) platform to calculate MRT values. By integrating these two impacting factors, this research provides insights into the potential future changes in MRT levels and the resulting thermal conditions and geohazards in the study area. The analysis enables the identification of areas susceptible to increased radiant heat exchange due to the proposed changes in land cover, urban morphology, and air temperature. Furthermore, this study contributes to a better understanding of the complex interactions between climate change, urbanization, and urban microclimates. By incorporating MRT assessments and prioritizing thermal comfort, cities can develop strategies to mitigate the negative effects of UHI and create sustainable and livable urban environments for future generations. Full article

Afghanistan is located on the Eurasian tectonic plate’s edge, a highly seismically active region. It is bordered by the northern boundary of the Indian plate and influenced by the collisional Arabian plate to the south. The Hindu Kush and Pamir Mountains in Afghanistan are part of the western extension of the Himalayan orogeny and have been uplifted and sheared by the convergence of the Indian and Eurasian plates. These tectonic activities have generated numerous active deep faults across the Hindu Kush–Himalayan region, many of which intersect Afghanistan, resulting in frequent high-magnitude earthquakes. This tectonic interaction produces ground shaking of varying intensity, from high to moderate and low, with the epicenters often located in the northeast and extending southwest across the country. This study maps Afghanistan’s tectonic structures, identifying the most active geological faults and regions with heightened seismicity. Historical earthquake data were reviewed, and recent destructive events were incorporated into the national earthquake dataset to improve disaster management strategies. Additionally, the study addresses earthquake hazards related to building and infrastructure design, offering potential solutions and directions to mitigate risks to life and property. Full article

Peak Ground Acceleration (PGA) is a measure of the maximum ground shaking intensity during an earthquake. The estimation of PGA in areas affected by earthquakes is a fundamental task in seismic hazard assessment and emergency response. This paper presents an automated service capable of rapidly calculating the PGA’s values in regions impacted by seismic events and publishing its results on an interactive website. The importance of such a service is discussed, focusing on its contribution to timely response efforts and infrastructure resilience. The necessity for automatic and real-time systems in earthquake-prone areas is emphasized, enabling decision-makers to assess damage potential and deploy resources efficiently. Thanks to a collaboration agreement with the Civil Protection Department, we are able to acquire accelerometric data from the Italian National Accelerometric Network (RAN) in real time at the monitoring center of the Osservatorio Vesuviano. These data, in addition to those normally acquired by the INGV network, enable us to utilize all available accelerometric data in the Campi Flegrei area, enhancing our capacity to provide timely and accurate PGA estimates during seismic events in this highly active volcanic region. Full article

The central Ionian Sea is one of the most seismogenic areas in the Mediterranean Sea region. In particular, the island of Lefkada, Greece, has experienced many catastrophic earthquakes. The historical seismicity of Lefkada has been revised by utilizing published and little-known macroseismic information sources, e.g., administrative documents, letters, marginal notes, and eyewitness accounts. We organized a new descriptive and parametric catalogue of 44 earthquakes that had their maximum macroseismic intensity in Lefkada and covered the time interval from the 15th century A.D. up to 1911. Earthquake dates, origin times, intensities, magnitudes, and epicentral coordinates were estimated or revised. Magnitudes estimated in previous catalogues in general are larger with respect to our magnitude determinations, possibly due to different calculation methods. The descriptive part of the catalogue includes descriptions of the earthquakes’ impact on buildings and of environmental effects, e.g., landslides and local tsunamis. The catalogue completeness gradually increases with time but is likely complete for the entire period examined lower magnitude threshold M_w = 6.0. One important yet puzzling earthquake is the large one that reportedly ruptured the Strait of Otranto and damaged an unprecedentedly extensive region in Italy, Albania, and Greece, including Lefkada, on 9/20 February 1743. Little-known documents revealed that the heavy destruction supposedly caused in Lefkada was very likely due to amalgamated information regarding local earthquakes and the large one. Full article

The NNW-trending Central Mindoro Fault (CMF) is an active oblique left-lateral strike-slip fault as determined from offset morphotectonic features such as spurs and streams. Mapping of the trace and determination of the sinistral strike-slip sense of motion of the CMF is essential not only to the assessment of hazards but also to providing a clearer perspective of its role in accommodating deformation resulting from the NW relative motion between the Philippine Sea Plate and the Sunda Plate. Its sense of motion is also kinematically congruent with the NW-SE translation along a transcurrent zone between the Philippine Mobile Belt and the Palawan Microcontinental Block on the western part of the Philippine archipelago. It is also consistent with the left-lateral motion of other structures within the zone, such as the Verde Passage Fault—another structure believed to be accommodating the NW-SE translation. Mapping of the CMF provides a key constraint in identifying the possible mechanism(s) involved in the dextral strike-slip motion of the 1994 Mindoro Earthquake ground rupture, which is subparallel to the CMF. Full article

To reduce earthquake damage and its effect on the structures, tuned mass dampers (TMDs) are generally positioned on the top of the structures for effectiveness, but existing TMDs on the story levels have problems due to space and additional vertical load issues. Underground-tuned mass dampers (UTMDs) can be used for base-isolated structures to limit deformations of base isolation systems. This study aims to determine the optimum design parameters of an underground tuned mass damper (UTMD) combined with based isolated systems. The best-performing algorithm among the metaheuristic algorithms selected for the optimal design of the UTMD system was investigated. Classical and hybrid forms of several metaheuristic algorithms were used in the methodology. The hybrid of the Jaya algorithm and Teaching Learning-Based Optimization was found to be the most effective one for the reduction of maximum accelerations. The cases limiting the damping of the base-isolation system and various mass ratios of UTMD were also conducted. In conclusion, the control system can reduce the maximum acceleration of the optimum base-isolated structure by 4% to 23% according to the mass ratio of UTMD and provide a low-damping isolation design as the optimum one. Full article

The use of a dense network of commercial high-cost seismographs for earthquake monitoring is often financially unfeasible. A viable alternative to address this limitation is the development of a network of low-cost seismographs capable of monitoring local seismic events with a precision comparable to that of high-cost instruments within a specified distance from the epicenter. The primary aim of this study is to compare the performance of an advanced, contemporary low-cost seismograph with that of a commercial, high-cost seismograph. The proposed system is enhanced through the integration of a 24-bit analog-to-digital converter board and an optimized architecture for a low-noise signal amplifier employing active components for seismic signal detection. To calibrate and assess the performance of the low-cost seismograph, an installation was deployed in a region of high seismic activity in Evgiros, Lefkada Island, Greece. The low-cost system was co-located with a high-resolution 24-bit commercial digitizer, equipped with a broadband (30 s—50 Hz) seismometer. An uninterrupted dataset was collected from the low-cost system over a period of more than two years, encompassing 60 local events with magnitudes ranging from 0.9 to 3.2, epicentral distances from 5.71 km to 23.45 km, and focal depths from 1.83 km to 19.69 km. Preliminary findings demonstrate a significant improvement in the accuracy of earthquake magnitude estimation compared to the initial configuration of the low-cost seismograph. Specifically, the proposed system achieved a mean error of ±0.087 when benchmarked against the data collected by the high-cost commercial seismograph. These results underscore the potential of low-cost seismographs to serve as an effective and financially accessible solution for local seismic monitoring. Full article

During winter 2023–2024, the Charente River experienced four successive flood events in six months, including one major flood and three moderate ones. These grouped floods affected a huge territory in the Charente valley, in particular the Territoire à Risque d’Inondation Important (TRI, i.e., Major Flood Risk Area) between Angoulême and Saintes (46 municipalities). Although they produced little immediate damage due to their slow kinematics and low flow speeds, they had a major impact on the functioning of the territory through prolonged house flooding and infrastructure disruption. This repeated flood sequence is all the more remarkable in that it occurs after the February 2021 extreme flood and a backdrop of severe and prolonged drought initiating in 2019. This article proposes to analyze grouped floods, a complex and little-studied hydrological phenomenon, from a geohistorical perspective in order to demonstrate that they are not emergent events and to look for historical precedents that show that these particular events have already occurred in the past but have been neglected or underestimated until now. Among past grouped flood sequences extending back to 1700, a significant similarity arises with the 1859–1860 flood sequence. In both cases, the first annual flood occurred early in the year in response to an early storm season and followed an uncommon hot and dry summer. Although the floods of 2023–2024 are well documented through both meteorological and hydrological data, as well as the surrounding context, the floods of 1859–1860 remain poorly constrained. By gathering a wide range of documentary sources and instrumental data, we try to better understand the context and the course of this past sequence of grouped floods, with particular emphasis on the first annual flood, the November 1859 flood. The analysis of similarities and divergences between sequences of past and recent grouped floods makes it possible to improve knowledge of their formation and course in order to better anticipate these particular events in the context of climate change. Full article

The Mekerra Basin in northern Algeria is highly vulnerable to severe flood events, such as those in October 1986 and September 1994, which caused significant damage to infrastructure and the environment. To address flood risk, this study applied the Rainfall–Runoff–Inundation (RRI) model to simulate hydrological processes and flood extents. The model was calibrated and validated using discharge data from these historical events. The sensitivity analyses identified hydraulic conductivity, suction head, and channel roughness as key parameters influencing flood peaks. The RRI model demonstrated a strong performance, achieving correlation coefficients of 0.97 and 0.94 for the 1986 and 1994 events, respectively. The model also produced R² values of 0.94 (calibration) and 0.89 (validation), with Percent Bias (PBIAS) values of 0.006 and 0.013, indicating minimal bias. Nash–Sutcliffe Efficiency (NSE) scores of 0.93 (calibration) and 0.86 (validation) confirmed its robustness in simulating event flows. This study represents the first application of the RRI model in the Mekerra Basin and highlights its utility for flood risk assessment in arid and semi-arid regions, offering critical insights for flood management and mitigation strategies. Full article

Since the turn of the 20th century, glacial thinning has been exposing volcanic mountain slopes around Iceland’s outlet glaciers. In the early 2000s, several slope instabilities appeared around the Svínafellsjökull outlet glacier in Southeast Iceland. The largest of these is located on a slope called Svarthamrar and is defined by a more than 2 km-long fracture system that separates the northernmost part of the mountain, south of Svínafellsjökull. Here we present updated glacier bed topography, a stratigraphical and structural assessment of the Svarthamrar slope, and quantify the destabilizing effect of glacial unloading from 1890 to deglaciated. Our results show that the slope was predisposed to instability by structural discontinuities and a strongly overdeepened glacial trough. Glacial unloading likely controlled the slope destabilization, potentially exacerbated by temporarily steeper hydraulic gradients due to rapid glacier thinning in the late 1990s and 2000s. The load of older landslide deposits on the glacier acts stabilizing on the slope. We propose that future glacial thinning will reduce the slope stability further, making it more susceptible to external triggers, and resulting in reactivation of the deformation and potential failure. Similar trends of destabilization can be expected for many slopes in Iceland and elsewhere. Full article