Search Results (2,474)

Accurate landslide identification is crucial for enhancing emergency response capabilities during destructive geological hazards. Although deep-learning-based semantic segmentation has demonstrated effectiveness, substantial variations in landslide scales and environmental similarities continue to challenge existing methods. This paper systematically constructs a new co-seismic landslide dataset for the Yarlung Zangbo River basin based on the 2017 Nyingchi earthquake, effectively filling a critical regional data gap. This paper proposes CETransUNet (coordinate attention and edge-guided attention transformer UNet), a novel landslide detection model that integrates ResNet and Transformer architectures. Specifically, a coordinate attention (CA) module is introduced within the skip connections between the encoder and decoder. This module encodes positional information along both horizontal and vertical spatial directions and dynamically re-weights the feature maps, thereby effectively suppressing background noise caused by semantic gaps and enhancing the model’s ability to localize landslide regions. Additionally, an edge-guided attention (EGA) module is incorporated into the decoder. This module extracts explicit edge priors from the input image using a Laplacian operator and imposes geometric constraints on the predictions via a boundary reverse attention mechanism, thereby significantly alleviating boundary ambiguity and morphological distortion of landslides. Evaluations across datasets from the Yarlung Zangbo River, Iburi-Tobu, and Bijie regions demonstrate that CETransUNet significantly outperforms state-of-the-art models—including TransUNet, SegFormer, and SwinUNet—in terms of IoU, MIoU, and F1-score. Overall, through the synergistic optimization of the coordinate attention and edge-guided attention modules, the CETransUNet model achieves synchronous enhancement of boundary integrity and geometric precision in complex scenarios, providing a reliable technical solution for large-scale intelligent landslide identification. Full article

Cyclic triaxial tests are often used to evaluate the behavior of soils under seismic loads. The stress conditions imposed on a soil specimen during a cyclic triaxial test, however, are very different than those acting on an element of soil during an earthquake. One major difference is that the element in the field is subjected to a change in total confining stress, whereas in a conventional cyclic triaxial test the total confining stress (as applied through the cell pressure) is held constant. This use of constant cell pressure is usually justified by the assumption that in a saturated specimen the change in total stress is offset by a change in pore pressure, thus resulting in no change in the effective confining stress or liquefaction susceptibility. A laboratory study using cyclic triaxial tests was conducted on several soils to assess the validity of this assumption. For each soil, two series of stress-controlled cyclic triaxial tests were run: one set with a constant cell pressure, and thus a constant total confining stress, and a second set with a variable total stress/cell pressure. These tests were then compared in terms of both the resulting cyclic resistance curves and the amount of energy dissipated to trigger liquefaction. It was found that the two conditions of confining stress yielded results that were not statistically different. Therefore, the assumption that the change in pore pressure caused by the variation in total stress is offset by the change in pore pressure and thus results in no change in effective stress or liquefaction susceptibility appears valid. Based on these findings, cyclic triaxial tests performed with constant cell pressure, and thus a constant total confining stress, provide valid results for liquefaction analyses. Full article

The initial seconds after an earthquake are critical for rapid magnitude estimation to support real-time early warning. This study evaluates the determination of P-wave moment magnitude (M_wp) using strong-motion records from the 23 April 2025 Marmara Sea earthquake. High-quality accelerometric data from the Turkish National Strong Motion Network were analysed to extract early P-wave features within the first 3 s after P-wave onset. Results show significant rupture-directivity effects, whereby stations located approximately along the fault strike and rupture-propagation direction recorded larger ground-motion amplitudes and higher station-based Mwp estimates than stations located near nodal directions. The mean M_wp was 6.5 ± 0.2, consistent with the Global Centroid Moment Tensor (GCMT) moment magnitude estimate. Magnitude estimation was achievable within 8–20 s of P-wave arrival, confirming the method’s real-time applicability. Our findings demonstrate that strong-motion P-wave analysis can provide rapid and reliable magnitude estimates suitable for earthquake early warning, tsunami warning, and rapid-response applications. In the Marmara Sea region, where tsunami arrival times may be on the order of 20–30 min and critical infrastructure is concentrated in densely populated coastal areas, rapid determination of magnitude within seconds of earthquake initiation can provide valuable information for emergency management and hazard mitigation decisions. Full article

Remote-sensing land surface deformation (LSD) is a powerful and effective approach for investigating regional alpine permafrost variations. However, alpine permafrost is often distributed in areas characterized by earthquakes, and the LSD of alpine permafrost is potentially contaminated or diminished by earthquake-related LSD. Therefore, this study aimed to derive the effective LSD in the alpine permafrost of the Source Area Yellow River (SAYR) by removing LSD originating from the M_w 7.4 Maduo earthquake in 2021-05-22 and analyzing the spatiotemporal variations in LSD during 2017–2024. Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) was used to obtain the initial LSD time series from Sentinel-1 images acquired during 2017–2024. The LSD of the M_w 7.4 Maduo earthquake, its aftershocks and the post-seismic relaxation in SAYR was simulated separately by considering its temporal process and removed from the LSD time series in SAYR. The final LSD was validated against in situ Global Navigation Satellite System (GNSS) measurements, and the spatiotemporal variations in LSD in SAYAR were subsequently analyzed. The study found the following: (1) the removal of the earthquake-related LSD was successful both spatially and temporally and the final LSD has mean absolute error (MAE) of 3.22 mm and root mean squared error (RMSE) of 3.92 mm; (2) during 2017–2024, the vertical LSD in SAYR was mostly −8–8 mm/y; (3) soil moisture determined the spatial distribution of the LSD direction in SAYR as a result of local drainage conditions, air temperature, precipitation and snow melt. This study demonstrated the necessity of removing the earthquake-related LSD when investigating the alpine permafrost LSD in tectonically active areas. The strategy adopted in this study serves as a technical reference for future investigations of this kind. The findings in this study provide insight for a thorough understanding of permafrost evolution on the Tibetan Plateau in the context of climate change. Full article

Earthquake risk communication often remains centered on event parameters and structural collapse, while local site effects, building response and non-structural elements vulnerability shape how earthquakes are experienced and what people can do to reduce risk. This study examines whether a multi-modal, experience-based strategy focused on these dimensions, which are referred to as “last mile” of seismic risk, can improve public understanding and support actionable preparedness behaviors. The case study is the exhibition “Terremoti: Attenti agli Elementi!—Dettagli che salvano la vita” (Earthquakes: Beware of the Elements!—Details that Save Lives), designed for school audiences and the general public. Its effectiveness was assessed through five multiple-choice questions administered before (N = 183) and after (N = 174) the visit to the Genoa Science Festival; responses were analyzed overall and by topic and demographic group. Correct answers increased significantly from pre- to post-visit, with the largest gains concerning local site effects (+43.29%) and household prevention measures (+49.45%), whereas building vulnerability (+14.97%) and building dynamic response (+0.49%) showed more limited improvement. These exploratory results suggest that seismic risk communication is more effective when abstract concepts are translated into observable, manipulable, and everyday experiences, and support a shift toward a “last-mile” framework of seismic risk communication. Full article

This study investigated the dynamic performance of laminated veneer lumber (LVL) shear-walled structures retrofitted with an aluminum oxide (Al₂O₃) nanocoating through finite element analysis (FEA) using SAP2000 software. Later, the ground motion data from the 1968 Takochi-Oki earthquake was used to conduct linear assessments of the structure. LVL, a sustainable and high-performance timber material, was selected for its favorable strength-to-weight ratio and environmental advantages. Two structural models—a reference uncoated LVL structure and an Al₂O₃-coated counterpart—were analyzed to evaluate the influence of the nanocoating on modal and structural behavior. The Al₂O₃ coating, applied as a thin surface layer (0.002 m per side), was modeled to enhance stiffness and damping characteristics. Modal analysis revealed an increase in natural frequencies from 0.75–1.72 Hz to 1.19–2.85 Hz after coating, indicating improved rigidity. The maximum top displacement decreased by approximately 18%, from 77 mm to 65 mm, without significant mass addition. Additionally, von Mises stresses were reduced from 86.65 MPa to 8.03 MPa, confirming stress redistribution and improved structural stability. These results demonstrate that the Al₂O₃ nanocoating effectively enhances the stiffness, damping, and overall dynamic response of LVL shear walls. The proposed method offers a lightweight, non-invasive, and sustainable alternative to conventional retrofitting techniques, contributing to the development of resilient and eco-efficient timber construction systems. Full article

Integration of high-rate Global Navigation Satellite Systems (GNSS) with strong motion (SM) sensors enables accurate broadband coseismic displacements, which are critical for earthquake early warning and rapid source inversion. However, GNSS colored noise and SM baseline shift can degrade the accuracy and stability of the integrated displacements. In this study, we propose a novel loose integration approach where a two-step Kalman filter (KF) is used. In the first step, the high-rate GNSS displacements without colored noise are estimated using an adaptive KF that parameterizes the colored noise. Then, the denoised high-rate GNSS displacements are integrated with SM in the second KF where the baseline shift in SM is parameterized as a random walk process. The effectiveness of the proposed method was validated with co-located high-rate GNSS and strong motion data collected from a shake table experiment, the 2010 Mw 7.2 El Mayor-Cucapah earthquake, the 2016 Mw 7.8 Kaikōura earthquake, and the 2019 Mw 7.1 Ridgecrest earthquake. The results show that the proposed method achieves an RMSE of 1.1 mm, a 21% improvement over the KFb solution when shake table recordings are used as the reference. Application to three real earthquake cases demonstrates that the method effectively mitigates low-frequency GNSS noise and SM baseline shift, resulting in more accurate and stable coseismic displacement estimates. Full article

The seismic fragility of reinforced concrete (RC) bridge piers is critical for urban rail transport systems, as severe pier damage may interrupt post-earthquake operation and threaten network safety. Compared with conventional highway bridge piers, urban rail transport RC solid piers usually have lower axial load ratios, larger cross-sections, and stricter serviceability requirements. However, the combined effects of geometric parameters, reinforcement detailing, and material strength on their cyclic behavior, dynamic response, and seismic fragility remain insufficiently understood. To address this issue, seven 1/4-scale RC solid pier specimens were tested under quasi-static cyclic loading to examine the effects of pier height, transverse reinforcement ratio, and longitudinal reinforcement ratio on damage evolution, hysteretic response, skeleton curves, and energy dissipation. A fiber-based OpenSees model considering bond-slip effects was then established, validated against the tests, and extended to a full-scale prototype pier for parametric analysis. The effects of aspect ratio, axial load ratio, longitudinal reinforcement ratio, stirrup ratio, steel yield strength, and concrete strength were evaluated under cyclic loading and nonlinear dynamic time-history excitations. An incremental dynamic analysis-based probabilistic seismic demand model was further developed using 30 near-fault ground motions, with peak ground acceleration as the intensity measure and displacement ductility as the engineering demand parameter. The results showed that increasing the aspect ratio changed the failure mode from flexure-shear-dominated to flexure-dominated behavior, increasing the ultimate displacement from 122 mm to 155 mm while reducing the peak lateral strength from 263 kN to 248 kN. Increasing the longitudinal reinforcement ratio improved both peak strength and ultimate displacement, from 226 kN to 262 kN and from 120 mm to 160 mm, respectively. The numerical results indicated that aspect ratio, axial load ratio, and longitudinal reinforcement ratio had more pronounced effects on seismic demand and fragility than stirrup ratio. Increasing steel yield strength generally reduced seismic fragility, whereas increasing concrete strength enhanced lateral resistance but did not necessarily improve fragility performance. These findings suggest that the seismic performance of urban rail transport RC solid piers should be evaluated by combining cyclic response, dynamic demand, and fragility-based performance, rather than by maximizing any single design parameter. Full article

Offshore high-pressure gas pipelines comprise critical infrastructure that often cross seismic regions for hundreds of kilometers. The intersection of such pipelines with seismic fault zones is frequently inevitable due to high costs or technical constraints of alternative routes. While typical mitigation measures, such as stronger materials or cross-sections and flexible joints, ensure pipeline integrity against earthquake-related geohazards, options for deep-water pipelines are more limited compared to onshore or even near-shore pipelines. This paper numerically investigates the efficiency of various mitigation approaches for surface-laid steel pipelines subjected to normal or reverse seismic faulting. Using ABAQUS finite-element software, the pipeline is simulated under realistic conditions for cohesive and non-cohesive seabed sediments. Critical fault displacements for different pipe steel materials, cross-sections, coatings, pressures, and orientations are calculated according to international standards. Results demonstrate that a 30° fault-pipe intersection angle is the most effective approach, increasing pipe’s capacity to fault dislocation by up to 90% for normal and 75% for reverse faults. Additionally, coating materials can increase a pipe’s resistance by up to 15%, whereas pressure difference variations may also have an impact. This study provides useful conclusions regarding the efficiency of the mitigation measures, the applicability of international standards, and the simulation of pipe–soil interaction. Full article

Prefabricated reinforced concrete (RC) buildings comprise the majority of industrial buildings in Türkiye. Over the past thirty years, many of these buildings have suffered severe damage or partial/total collapse during the devastating earthquakes due to inadequate design. Similar problems were highlighted again during the Kahramanmaraş earthquake sequence (Mw 7.8 and 7.7) on 6 February 2023. This study examines the seismic performance and retrofitting of four single-story prefabricated RC industrial buildings located in Tekirdag/Türkiye (designed and implemented) through nonlinear static (pushover) analyses. The case study buildings were selected from structures with Atcost and Lambda frame systems and parallel roof girder systems, originally designed for low-seismicity regions and adopted from Northern European countries without seismic detailing or modification. The buildings were investigated in detail through on-site surveys and material testing, which revealed critical deficiencies. In addition, a hybrid retrofitting strategy was adopted. This strategy combined the use of CFRP wrapping to enhance ductility at column–beam joints, with vertical and roof-level steel braces and frames to improve lateral stiffness. The findings show that the hybrid retrofitting approach offers an effective solution for prefabricated RC industrial buildings by simultaneously enhancing ductility and stiffness while meeting required performance targets without disrupting operations. Full article

Background: Adolescents are particularly vulnerable to psychological distress following natural disasters, especially in low-resource settings. This study examined the short-term psychosocial outcomes associated with Narrative Drawing Intervention (NDI), a structured, trauma-informed, school-based group counselling program integrating expressive drawing and guided narrative reflection, among students affected by an earthquake in rural western China. Methods: Using a quasi-experimental design, 30 trained educators facilitated eight NDI group sessions for 150 students. Of the 120 students who completed the intervention, a randomly selected subset completed standardized psychological assessments. The final analyzed sample included 64 participants (44 intervention; 20 control). Results: The intervention group demonstrated significant reductions in anxiety (p = 0.011, d = 0.40) and PTSD symptoms (p = 0.008, d = 0.42), with a reduction in stress approaching statistical significance (p = 0.063, d = 0.29). In contrast, the control group showed significant increases in anxiety, stress, and PTSD symptoms over the same period. Depressive symptoms did not significantly change in either group. Descriptive drawing comparisons indicated increased visual elaboration and more centralized figure placement following the intervention. Conclusions: Within the context of a quasi-experimental and exploratory design, the findings provide preliminary support for the feasibility of NDI and suggest potential short-term psychosocial benefits in post-disaster school settings. While baseline group differences and the lack of randomization suggest the need for further investigation, the results provide a foundation for future randomized and longitudinal studies that further examine causal pathways and the sustainability of observed effects. Full article

This paper presents the INFRARES tool, a fully parameterized, interactive, and freely available tool for the resilience assessment of bridges and tunnels within Greece’s transportation networks, under the impact of single or multiple hazards, including earthquakes and floods. The tool facilitates the application of a comprehensive methodology developed through the INFRARES project: Towards resilient transportation infrastructure in a multi-hazard environment research project. The resilience of each examined asset is quantified for the selected hazard scenario using a resilience index and a corresponding resilience grade. The INFRARES tool introduces two key innovations over previous approaches: first, it incorporates both structural and geotechnical components of bridges, overpasses, and tunnels in the vulnerability assessment step; second, it enables GIS-based visualization of the resilience index across selected single- or multi-hazard scenarios. In this context, INFRARES serves as a proactive decision-support tool, supporting authorities, infrastructure operators, and stakeholders to effectively assess, manage, and mitigate the impacts of diverse hazards on transportation systems, thereby enhancing the safety, reliability, resilience, and sustainability of transportation infrastructure under multi-hazard conditions. The proposed tool and the obtained results may support resilience-informed decision-making, prioritization of mitigation measures, and sustainable management of transportation infrastructure exposed to multiple natural hazards. Full article

Türkiye has many historically rich cities that host structures of significant cultural value. These structures, especially masonry bridges, reflect the construction techniques and materials of the periods in which they were built. However, studies on the origins of these bridges and the structural deteriorations that develop over time are limited. This situation may lead to damage and even the risk of collapse if necessary precautions are not taken. In this study, stone and mortar samples were first collected from the historic Pamukçular (Şifalısu) Bridge in Bitlis, and the collected materials were analyzed. The structural behavior of the bridge under seismic effects was then investigated using the Finite Element Method (FEM). A three-dimensional geometric model of the bridge was created, and material parameters were defined based on values from the material analyses. Static analysis under self-weight and modal analysis were performed in the ABAQUS software (Version 6.14) to obtain the natural frequencies. Under the bridge’s self-weight, local stress concentrations were concentrated at the arch crown and pier-arch connections, with maximum tensile and compressive stresses reaching approximately 0.15 MPa and 0.27 MPa, respectively. These low stress levels demonstrate that the structure remains fully stable under static loading conditions. Finally, dynamic analyses in the time domain were carried out. In these analyses, records from the 2011 Van Earthquake and the 2023 Kahramanmaraş Earthquake were used to identify the bridge’s critical regions and evaluate its seismic performance. The results indicate that the overall structural stability is adequate; however, local stress concentrations occur in the arch crown and pier connection regions. The study provides engineering-based recommendations for preserving and strengthening historic masonry bridges. Full article

Coastal continuous girder bridges are exposed to coupled environmental and seismic hazards during long-term service, including chloride-induced corrosion, freeze–thaw damage, scour, near-field ground motions, and structural irregularity. These factors can progressively reduce structural capacity, amplify seismic demand, redistribute component responses, and affect post-earthquake functionality and recovery. This paper reviews recent advances in the time-dependent seismic vulnerability and resilience assessment of reinforced concrete and prestressed concrete coastal continuous girder bridges. Based on 229 screened publications, the review first summarizes deterioration mechanisms and modelling approaches for chloride corrosion, freeze–thaw damage, and scour, with emphasis on their effects on material degradation, component capacity, foundation restraint, and seismic fragility. The demand-side effects of near-field vertical excitation and pulse-like ground motions are then discussed, followed by the seismic response characteristics of irregular continuous girder bridges, including curved alignments, unequal pier heights, and skewed supports. Existing studies indicate that environmental deterioration can shift fragility curves toward lower intensity levels, near-field vertical excitation can modify axial force, bearing contact state, girder–bearing separation, and impact response, while structural irregularity may concentrate seismic demand in critical components. Furthermore, the review clarifies the transition from time-dependent fragility analysis to functionality loss, recovery modelling, and lifecycle resilience assessment. The main research gaps include simplified deterioration representation, insufficient coupling of deterioration–hazard–irregularity effects, limited validation of time-dependent fragility models, and weak integration between component damage, bridge functionality, recovery trajectories, and resilience indicators. Future studies should develop more unified, uncertainty-informed, and lifecycle-oriented frameworks for coastal bridge vulnerability and resilience assessment. Full article

Seismic isolation systems are widely adopted in bridge engineering to reduce earthquake-induced force transfer and improve structural resilience. Conventional lead rubber bearings (LRBs) provide effective energy dissipation and period elongation; however, their limited recentering capability may result in significant residual displacement after strong ground motions. This study investigates the seismic performance of a two-level shape memory alloy–lead rubber bearing (TL-LRB-SMA) hybrid isolation system for multi-span bridges considering structural flexibility, support compliance, and geometric irregularity. A nonlinear analytical model of the hybrid isolator was developed and validated under cyclic loading using benchmark hysteretic behavior from the literature. Subsequently, a multi-degree-of-freedom numerical model of an eleven-span benchmark bridge was established and verified through modal analysis, equivalent static analysis, and comparison with MSBridge software (MSBridge Beta 1.0.1). Nonlinear time-history analyses were performed using multiple excitation scenarios, including the 1940 El-Centro record, Kobe ground motion, oblique seismic incidence, and combined loading cases. Flexible foundation conditions were represented using equivalent translational soil springs. The results indicate that the TL-LRB-SMA system consistently improves self-centering performance and significantly reduces residual displacement relative to conventional LRBs. For the regular bridge with 48 ft piers, residual displacement decreased from 0.786 inches to 0.268 inches under El-Centro excitation, while under combined excitation it reduced from 0.264 inches to 0.087 inches. For irregular bridge configurations, substantial residual displacement reductions were also observed under both longitudinal and oblique loading. Although moderate increases in peak displacement occurred in some cases due to staged SMA activation, the overall recentering performance improved markedly. Overall, the proposed TL-LRB-SMA system demonstrates strong potential for enhancing seismic resilience and post-earthquake serviceability of bridge structures, particularly in flexible and irregular configurations. Full article