Search Results (173)

The Nujiang Fault Zone is located in the Three Parallel Rivers region on the southeastern margin of the Qinghai–Tibet Plateau, serving as a discordogenic fault that must be traversed by the Sichuan–Tibet transportation corridor project. Because of the scarcity of direct geological evidence, the late Quaternary activity of the Nujiang Fault Zone remains highly controversial. Focusing on the late Quaternary activity and active intensity of this fault, we conducted detailed field investigations along the Zuogong segment of the Nujiang Fault Zone based on high-resolution remote sensing images. Two trenches were excavated within a linear trough near Ranmi Village. Fourteen ¹⁴C samples were collected for AMS dating, and two fault gouge samples were obtained for microstructural analysis, aiming to reconstruct the paleoseismic sequence and estimate the corresponding earthquake magnitude. Clear fault planes were exposed in the trenches, which distinctly offset the middle-late Holocene strata. Three paleoseismic events were recorded by trench exposures: Event E1 prior to 5824 ± 61 cal BP (approximately 7031 ± 688 cal BP), Event E2 at 4560 ± 321 cal BP, and Event E3 at 1464 ± 142 cal BP. Analogous to the northern-central segment of the Longmenshan Fault Zone, where the Ms 8.0 2008 Wenchuan earthquake occurred, and its southern segment was associated with the Ms 7.0 2013 Lushan earthquake, microstructural observations of the fault gouge from the Zuogong segment also revealed typical brittle deformation characteristics. In terms of trenching-offset features, as well as the composition and microscopic properties of clay minerals in the fault gouge, the Zuogong segment exhibited geological signatures that were intermediate between the southern and northern-central segments of the Longmenshan Fault Zone, with greater similarity to the southern segment. Accordingly, the maximum potential earthquake magnitude of this segment was estimated to be Ms 7.0–7.5. The paleoseismic sequence of the Zuogong segment indicated an earthquake recurrence interval of approximately 2500–3000 years, with approximately 1500 elapsed years since the most recent seismic event. Although the full recurrence cycle has not yet been approached, implying low probability of great earthquakes with magnitudes of Ms 7.0–7.5 in the near future, the occurrence of non-characteristic seismic events cannot be ruled out. This study reveals direct evidence for Holocene activity along the Zuogong segment of the Nujiang Fault Zone, providing a critical scientific basis for quantitative seismic hazard assessment and major engineering planning and construction in the research area. Full article

Transportation infrastructure networks are increasingly exposed to multiple natural hazards, thus demanding sophisticated assessment methodologies for evaluating compound threats and supporting decision-making. This paper presents an operational multi-hazard assessment framework integrating the Analytical Hierarchy Process (AHP) with Weighted Linear Combination (WLC) within a GIS-based decision support system. The methodology is implemented as a plugin for CI-RES (critical infrastructure resilience), a web-based geospatial platform developed by ENEA for integrated analysis and resilience assessment of critical infrastructure systems, enabling automated evaluation of infrastructure elements against six natural hazards: seismic, flood, landslide, volcanic, wildfire, and tsunami. The approach combines spatial analysis with multi-criteria decision-making techniques, allowing users to define hazard priorities through pairwise comparison matrices while ensuring consistency through automatic validation procedures. A comprehensive case study covering the Italian national territory demonstrates the framework’s ability to process large-scale infrastructure datasets, generating spatially explicit hazard maps and statistical summaries. Our results reveal significant variations in multi-hazard exposure across different infrastructure types and geographic regions, with approximately 48% of the analysed road network falling within medium-to-high multi-hazard zones, 58% of road bridges and viaducts, 46% of railways, and 66% of railway bridges. The integration within the CI-RES platform provides stakeholders with an accessible web-based interface for conducting multi-hazard assessments, supporting evidence-based infrastructure planning and emergency management decisions. This work contributes both methodologically, through the AHP–WLC integration, and practically, through its implementation in an operational decision support system. Full article

Coastal lagoon Salt Ponds are highly valuable wetland systems where traditional salt production coexists with ecosystems of significant ecological importance, often characterized by high environmental sensitivity. In data-scarce coastal settings, particularly those located near river channels and drainage networks, assessing multiple environmental hazards remains a major challenge. This study proposes a simplified and transferable methodological framework for multi-hazard assessment in coastal Salt Pond environments (DAFFLE; Data Acquisition Fluvial Flooding and Liquefaction Evaluation), with particular emphasis on areas where field data are limited and fluvial processes and seismic effects may interact. The approach integrates three main components: first, improved terrain modelling using global elevation datasets and ICESat-2 laser altimetry data to better represent very flat coastal areas; second, flood hazard simulation by modelling water depths under different flood scenarios to map potential inundation; third, liquefaction susceptibility is assessed using surficial geological data and key geomorphological parameters, producing simplified probabilistic hazard maps informed by existing seismic hazard datasets or scenario-based assumptions. The proposed framework provides a scalable and practical tool for first-order multi-hazard assessment in vulnerable coastal Salt Pond environments. It supports comparative hazard analyses and decision-making in regions where detailed site-specific data and extensive field investigations are not available, offering a consistent baseline for coastal lagoon Salt Pond risk evaluation and management. Full article

The Upper Yellow River Basin (UYRB) is one of the most tectonically complex and seismically active regions in China, but the detailed crustal deformation and interseismic fault couplings, providing the essential parameters for geodynamics and seismic hazard analysis, are still unclear in this region. We thus adopt Sentinel-1 Synthetic Aperture Radar images to form frame-based line-of-sight velocity maps, and then derive a high-resolution surface deformation map around the UYRB. Slip rates and coupling states are further inverted for some active yet less-investigated faults. For instance, we estimate a right-lateral strike-slip motion of ~2.3–3.5 mm/yr along the Riyueshan Fault, and a thrust rate of ~2.0–3.5 mm/yr across the Lajishan Fault. Finally, the seismic moment budgets and the potential magnitudes are calculated based on the fault slip deficits and historical earthquakes. The accumulated moment deficit could produce earthquakes of M_W ≥ 6.0 in most active faults, and up to M_W ≥ 7.0 along the Dongdatan-Xidatan and Maqin-Maqu segments of the East Kunlun Fault and the Jinqianghe segment of the Haiyuan Fault. Our inverted slip rates, interseismic coupling states, and potential seismic moment on the active faults provide a basis for understanding kinematic processes and assessing seismic hazards within the UYRB. Full article

Near-fault ground motions influenced by rupture directivity impose seismic demands that differ fundamentally from those associated with conventional far-field earthquakes, particularly in terms of displacement-controlled response. This study presents a performance-based seismic assessment of existing reinforced concrete (RC) buildings subjected to near-fault ground motions in the Sivrice–Pütürge segment of the Malatya–Ovacık Fault Zone, Eastern Anatolia. A probabilistic seismic hazard analysis (PSHA) was performed using NGA-West2 ground-motion prediction equations together with a regionally defined fault model, and the resulting hazard was evaluated within the framework of the Turkish Building Earthquake Code (TBEC-2018). Code-compatible earthquake records were selected and scaled for the DD-2 design earthquake level, while rupture directivity was represented using a literature-based median amplification factor. Nonlinear time-history analyses were subsequently carried out for three existing RC buildings representing low-, mid-, and high-rise structural typologies. Structural performance was evaluated in terms of roof displacement, interstory drift ratio, base shear, and element-level damage states. The maximum roof displacements reached 0.070 m, 0.107 m, and 0.138 m for the low-, mid-, and high-rise buildings, respectively, corresponding to maximum drift ratios of 0.60%, 0.46%, and 0.34%. The results indicate that rupture directivity has only a limited influence on base shear demand but substantially increases displacement-related response quantities and promotes a redistribution of structural damage from predominantly beam-controlled behavior toward increased participation of columns and shear walls, particularly in medium- and high-rise buildings. These findings demonstrate that conventional code-based assessment procedures may underestimate deformation demands in fault-proximal regions and highlight the importance of explicitly considering rupture directivity in the seismic performance assessment of existing reinforced concrete buildings. Full article

Landslides are among the most destructive geological hazards, posing significant threats to human life, infrastructure, and ecological environments. In this research, to improve the accuracy and reliability of landslide susceptibility assessment, Guangdong Province was selected as the study area, and a multi-source environmental factor dataset incorporating topographic, geological, hydrological, climatic, vegetation, and anthropogenic factors was constructed. Geological factors, including fault distance and seismic point distance, were introduced to characterize the influence of tectonic activities on slope instability. A landslide inventory and a non-landslide sample dataset were established for model training and validation. The Extreme Gradient Boosting (XGBoost) model was employed for landslide susceptibility mapping, and SHapley Additive exPlanations (SHAP) analysis was used to interpret the contribution of different conditioning factors. The results showed that the model achieved an area under the receiver operating characteristic curve (AUC) of 0.8335 on the independent test dataset and a mean AUC of 0.8457 ± 0.0219 for a five-fold stratified cross-validation. The high-susceptibility areas were primarily distributed in the mountainous and hilly regions of northern and eastern Guangdong Province. Vegetation-related variables, road proximity, land-cover type, slope, and distance to coal mines were identified as important contributors to landslide occurrence. This study provides useful references for geological hazard prevention, risk management, and sustainable regional planning. Full article

This study offers a new approach to probabilistic earthquake hazard assessment (PEHA) in the densely populated regions of Southern Sumatra and West Java, Indonesia. While much attention is given to powerful, offshore megathrust earthquakes, this research focuses on a different yet equally dangerous threat: shallow, moderate-magnitude earthquakes (4.5 ≤ M_w ≤ 6.5) that occur on land. These events, often caused by unmapped faults, pose a significant risk due to their proximity to major cities and infrastructure. To develop a more reliable model, a best-fit earthquake rate model was estimated using declustered shallow earthquake events as a reference. This model enhances existing methods by offering a more precise depiction of where these shallow, damaging earthquakes are likely to occur. We accomplished this by analyzing a comprehensive probability of exceedance (PoE) of earthquakes with magnitudes up to 6.5 and depths up to 50 km that occurred between 1963 and 2022, mapping and modeling both the known active faults and the historical seismic activity in the region, and using advanced statistical methods to create a highly reliable, integrated seismicity rate model. The final product, the Integrated Most Reliable Spatial Seismicity Rate Model (Model_IMRSSR), is proposed as a useful tool for government authorities and urban planners. It can be used to create detailed seismic hazard maps that highlight areas of highest risk, especially those with unmapped faults. By guiding development away from these high-risk zones and identifying specific locations for physical reinforcement, this research provides a framework for sustainable investment. The proactive use of these findings can lead to more resilient communities and a significant reduction in potential damage and loss of life from future earthquakes. Full article

The High Agri Valley (HAV, Southern Italy) comprises the largest onshore oil field in Europe and has both significant geothermal extraction potential and one of the highest seismic hazards in Italy, as demonstrated by the 1857 Mw 7.0 Basilicata earthquake. However, seismic imaging and geological mapping have so far produced insufficient evidence regarding the location of fluid reservoirs and human-induced migration pathways within the HAV’s tectonic structures. Here, a 3D scattering and absorption tomography, proxy for heterogeneities and fluid content, respectively, detects hydrocarbons and potential geothermal resources within the Apulian Platform. Seismic scattering differentiates the low-scattering Irpinia tectonic mélange, which deepens in the center of the valley, from the fractured high-scattering carbonates of the Apulian Platform. Seismic absorption identifies regions of fluid reinjection, as demonstrated by the Costa Molina 2 case study, and reveals the preferred pathways for fluids that induce seismicity due to seasonal variations in the water level of the Pertusillo artificial lake. The integration of scattering and absorption imaging with direct well information, geochemical and hydrological models, could provide a powerful tool for both seismic hazard assessment and the exploration of sustainable energy resources. Full article

Lake Sarez in Tajikistan, formed by a major earthquake-induced landslide in 1911, is located in the highly seismically active Pamir–Hindu Kush region. The lake is impounded by the Usoi Dam, one of the largest natural landslide dams in the world, which has raised concerns regarding its long-term stability and associated downstream flood hazards. Due to its geomorphological setting and potential exposure to multiple triggering mechanisms, including seismic activity and landslides, Lake Sarez is widely considered a high-consequence hazard system. Although the dam has remained stable for over a century and is currently monitored using modern geodetic and satellite-based technologies, uncertainties remain regarding its internal structure and response to extreme external forcing. While existing early warning systems enhance preparedness in downstream communities, effective long-term risk reduction requires continued monitoring, improved hazard modeling, and strengthened regional cooperation. This review synthesizes existing studies on the geological setting, hazard potential, stability assessments, and disaster risk management strategies related to Lake Sarez. It highlights the importance of integrated multi-hazard analysis and precautionary risk governance in managing low-probability but high-impact natural dam failure scenarios. Full article

A catastrophic Ms7.8 earthquake occurred in Tangshan in 1976 at a focal depth of approximately 12 km, resulting in severe casualties and substantial economic losses. Given its unique tectonic setting, the seismogenic structure and dynamic genesis of the Tangshan earthquake have long remained a key research topic in seismotectonic studies. To better characterize the tectonic framework, seismogenic mechanisms, and deep–shallow dynamical coupling within the Tangshan seismic zone, we employ multi-scale wavelet decomposition on high-resolution residual gravity anomalies to isolate crustal structure signals across different depth ranges. Integrating these structural signatures with the spatial distribution of seismicity yields a comprehensive framework for interpreting the regional tectonic evolution. The Tangshan seismic zone is positioned within the intricate structural architecture of the Tangshan rhombic fault block, a system embedded within the broader context of the North China Craton (NCC) destruction. Seismicity displays a distinct preferred orientation, with events concentrated along block-bounding faults and gravity anomaly gradient zones. With increasing wavelet decomposition levels, the gravity anomalies exhibit a systematic transition from spatially dispersed patterns associated with shallow structures to more concentrated features reflecting deeper geological domains. Shallow anomalies from the first to third decomposition orders, which are primarily controlled by Quaternary sedimentary layers, show a fragmented distribution that corresponds well with the development of local flower structures and the occurrence of diffuse shallow seismicity. The fourth- to seventh-order anomalies clearly delineate the rhombic block and its bounding peripheral faults, highlighting the structural intersections that hosted the Tangshan mainshock and its associated aftershock sequence. In contrast, the eighth- to tenth-order deep-seated anomalies corresponding to deeper structural levels exhibit pronounced coalescence, effectively imaging mantle upwelling and large-scale density heterogeneities within the lithospheric mantle. These concentrated gravity highs are closely coupled with mantle thermal activity, whose upward ascent induces thermal weakening of the lower crust and facilitates progressive stress transfer toward shallower crustal levels. Concurrently, frictional locking of shallow high-angle faults promotes intense stress accumulation within the rigid basement. The interplay between deep-seated dynamic concentration and shallow structural confinement ultimately triggers the catastrophic coseismic rupture responsible for the Tangshan earthquake. By delineating the structural transition from deep-seated aggregation centers to shallow dispersed fracture zones, this study establishes a robust framework for assessing seismogenic environments and regional seismic hazard potential across the progressively destroyed NCC. Full article

Cultural heritage assets in seismic metropolitan regions are increasingly exposed to interacting natural hazards, yet disaster risk assessments for historic buildings often remain limited to single-hazard interpretations. This study addresses this gap by developing a Geographic Information Systems (GIS)-based multi-hazard risk assessment for Ferhatpaşa Mosque, a sixteenth-century Ottoman heritage asset located in Çatalca, Istanbul. Eight spatial parameters were evaluated at the neighborhood scale: slope, elevation, aspect, precipitation, distance to fault lines, distance to hydrological features, land use, and soil capability. The model was developed through Weighted Overlay analysis and interdisciplinary expert-based weighting. Distance to fault lines and precipitation received the highest weights, each accounting for 17.22% of the model, followed by distance to hydrological features and soil capability, each weighted at 13.89%. The final risk map classified 71.99% of the study area as medium risk, 28% as low risk, and 0.02% as high risk. Ferhatpaşa Mosque was located within the medium-risk zone, approximately 29,600 m from active fault lines, 250 m from the nearest dry streambed, 800 m from the nearest stream, and 320 m from the nearest high-risk zone. These findings demonstrate that the mosque’s risk profile is shaped not by seismic proximity alone, but by the cumulative interaction of topography, precipitation, hydrology, soil conditions, and land-use characteristics. The proposed model provides a spatial decision-support framework for integrating cultural heritage conservation into sustainable disaster risk reduction and local risk mitigation planning. Full article

GNSS-derived strain-rate analysis, geodetic earthquake recurrence modeling, and seismic potential estimations were integrated to investigate segment-scale deformation behavior along the central North Anatolian Fault Zone (NAFZ) using a high-resolution geodetic velocity field. The obtained strain rates reveal that deformation within the central NAFZ is distributed across a geometrically complex and kinematically heterogeneous fault network rather than being restricted to the main fault strand alone. While the main fault accommodates the majority of regional deformation, significant strain accumulation is also observed along major splay fault systems, including the Merzifon–Esençay, Ezinepazarı, Sungurlu, Eldivan, and Ekinveren faults. The derived strain patterns further indicate the coexistence of localized transtensional and transpressional deformation regimes controlled by fault geometry, segment boundaries, and structural discontinuities. Geodetically derived earthquake recurrence periods display pronounced spatial variability, with shorter recurrence periods concentrated along the main fault strand and comparatively longer earthquake cycles characterizing structurally complex splay systems. Among the investigated structures, the eastern and central segments of the Merzifon–Esençay Fault (MEF) exhibit relatively elevated strain accumulation and seismic potential. In particular, the estimated potential earthquake magnitudes reaching Mw 7.3–7.5, together with paleoseismological evidence indicating that the most recent major surface-rupturing event along the Esençay segment occurred approximately 3700 years ago, suggest that this fault system may represent a candidate seismic gap within the central NAFZ. Overall, the results demonstrate that deformation within the central NAFZ is strongly partitioned among interacting fault segments and highlight the importance of segment-scale geodetic analyses for improving seismic hazard assessments in complex strike-slip fault systems. Full article

In this study, three-dimensional P- and S-wave velocity structures and P- and S-wave velocity ratio variations in the crust and upper mantle beneath the Marmara Region and the Sea of Marmara were modeled using the Poisson tomography method in the field of Seismology. Within this scope, P- and S-wave arrival times from a total of 23,672 earthquakes that occurred in the region between 2011 and 2023 were evaluated, and an inversion procedure based on body-wave arrival times was applied. The obtained results indicate that the northern branch of the North Anatolian Fault Zone is the most active segment among its three main branches. In addition, a low-velocity zone characterized by seismic gap features extending from the southern parts of Marmara toward Istanbul was identified. Within these seismic gap zones, P- and S-wave velocities decrease sharply across regions exhibiting strong velocity gradients. It was determined that this low-velocity structure cuts across the North Anatolian Fault, which branches into three segments within the Sea of Marmara, and continues at depths of approximately 15–25 km. Earthquakes were observed to concentrate particularly in areas with high-velocity ratio variations and within transition zones from low to high values. Due to the complex tectonic and stratigraphic structure of the Marmara Region, these low-velocity seismic gap zones within the crust may be associated with segments capable of generating large earthquakes in the future. Therefore, a detailed investigation of the crustal structure of the region provides important insights for understanding regional earthquake hazards. Full article

Earthquake-induced landslides represent a critical threat to transportation infrastructure in tectonically active mountainous regions, particularly in tropical volcanic settings where weak, highly weathered geomaterials dominate. This study develops an integrated framework that directly links physically based seismic threshold modelling with real-time landslide monitoring and operational early warning. The approach is demonstrated in the Cugenang area of Cianjur Regency, West Java, Indonesia, which was severely impacted by the moment magnitude (Mw) 5.6 earthquake in 2022. Slopes composed of highly weathered pyroclastic deposits [Plasticity Index (PI) = 54–68%; porosity > 60%] exhibit low shear strength and high sensitivity to seismic loading. Limit equilibrium analysis using the Morgenstern–Price method that combines the influence of seismic loading and groundwater conditions suggests that a horizontal seismic coefficient (kh) of approximately 0.06, corresponding to a Peak Ground Acceleration (PGA) of about 0.12 gravitational acceleration (g), is a critical threshold for initial landsliding. This comparatively low threshold challenges commonly reported values and demonstrates that slope failure in tropical volcanic terrains can occur under moderate ground shaking, reinforcing the need for site-specific hazard characterisation. The derived thresholds are operationalised within a multi-sensor early warning system integrating Micro-Electro-Mechanical Systems (MEMS) accelerometers and inclinometer measurements. Three hazard levels—Normal (<0.06 g), Alert (0.06–0.12 g), and Emergency (≥0.12 g)are combined with deformation thresholds [<10 milimeter (mm), 10–30 mm, >30 mm] to capture progressive failure processes and minimise false alarms. By coupling geotechnical modelling and real-time monitoring, this study provides a transferable and scalable framework for enhancing infrastructure resilience in landslide-prone regions. Full article

Seismically triggered landslides represent a major secondary hazard of earthquakes, often causing widespread damage over large areas. Rapid and reliable mapping of such phenomena is therefore essential, particularly in emergency contexts. While numerous studies have addressed landslide detection in vegetated regions using optical remote sensing, arid and desert environments remain relatively underexplored due to the limited spectral contrast between stable and failed slopes. In this study, we evaluate the potential of an automatic pixel-based method for the rapid detection of seismic landslides in arid settings, using high-resolution optical imagery. The analysis focuses on the Mw 5.5 earthquake that struck the Northern Red Sea Region of Eritrea on 26 December 2022. A detailed inventory of 1393 coseismic landslides was manually mapped from pre- and post-event PlanetScope multispectral images and used both for geomorphological and macroseismic analyses and as training data for a threshold-based classification approach. Landslide detection was based on changes in the Redness Soil Index (RSI) and its differential (ΔRSI), combined with a One-Class Asymmetric Robust Gaussian classifier. Results show a good capability to delineate landslide-affected areas, although commission errors remain significant. Despite these limitations, the proposed approach, still in need of a more trained implementation in the future, proves its potential effectiveness for rapid mapping purposes, owing to its simplicity and minimal computational requirements. These results open the possibility to implement a fully automatic methodology in the future, when more landslides will be mapped and a model trained on different and normalized datasets will be implemented. The results demonstrate that pixel-based optical methods, particularly those relying on red-band spectral changes, represent a valuable tool for the preliminary assessment of earthquake-induced landslides in arid environments and may support emergency response and first-order hazard evaluation. Full article