Search Results (732)

High-speed railway track–bridge systems (HSRTBSs) in near-fault high-seismicity regions face combined threats from pulse-type seismic excitations, vertical earthquake components and track defects, which may trigger structural damage and deterioration of track regularity. This paper establishes refined OpenSEES coupled numerical models for a typical 32 m simply supported girder bridge equipped with CRTS II slab ballastless track, considering both conventional spherical steel bearings and friction pendulum bearings (FPBs). Nonlinear time-history analyses are performed with near-fault pulse-like and far-field non-pulse ground motions to explore the influences of peak ground acceleration (PGA), vertical-to-horizontal acceleration ratio (αVH), and CA mortar void length. The results demonstrate hierarchical controlling effects of these parameters. PGA dominates the overall seismic response; sliding layer damage follows the sensitivity sequence PGA > αVH > CA mortar void, whereas post-earthquake traffic capacity degradation obeys PGA > CA mortar void > αVH. Near-fault pulse-like ground motions produce more severe structural damage compared with far-field inputs. FPB isolation yields a maximum pier-top seismic reduction ratio of 86.73% and effectively mitigates structural deformation, but cannot eliminate track irregularity originating from CA mortar void defects. Conditional on the 0.2 g seismic level and the given structural configuration adopted in this study, αVH = 0.65 and the 1.95 m critical CA mortar void length for longitudinal track constraint failure can serve as reference values, though they are not universally applicable for all track–bridge systems. This work provides insights for seismic design, CA mortar defect remediation and post-earthquake traffic assessment of near-fault isolated HSRTBSs. Full article

To clarify the stage-dependent stress superposition in gob-side roadways beneath irregular overlying goafs, the #52109 material roadway was investigated using a MATLAB-based analytical stress-transfer model, key-strata mechanics, FLAC3D simulation, and field monitoring. The analytical results revealed an approximately elliptical “stress-bubble” distribution with a maximum increment of 4.82 MPa beneath the overlying remnant coal bodies and a second roof-induced stress peak of 1.22 MPa at 14.88 m from the adjacent goaf boundary, governed mainly by Sub-key Strata 2 and 3. At the actual vertical separation of 71.5 m between the roof of the #52109 material roadway and the base of the overlying goaf, the two stress-component curves calculated in MATLAB intersected at 59.1 m from the projected boundary of the overlying remnant coal body, defining a site-specific transition between the dominant stress sources. Beyond 59.1 m, the lateral abutment stress induced by the #52107 goaf was dominant; within this distance, the downward-transmitted stress from the remnant coal body increased rapidly and was superimposed on the lateral abutment stress. The analytical and FLAC3D models predicted maximum total vertical stresses of 32.19 and 32.51 MPa, respectively, with a difference of 0.32 MPa (0.99%); the numerical model also qualitatively reproduced the corresponding spatial transition in the stress pattern. The combined results identified the sections 250–485 m and 680–1305 m from the roadway entrance as high-hazard zones. After targeted large-diameter borehole destressing and roof pre-splitting blasting were implemented, field monitoring recorded a maximum side deformation of 77.9 mm, while low-energy seismic events accounted for 94.33% of all monitored events. These findings provide a quantitative basis for hazard zoning and regional pressure relief in gob-side roadways beneath irregular overlying goafs. Full article

The Longmenshan Fault Zone, as the steep boundary on the eastern edge of the Qinghai–Xizang Plateau, is the seismogenic structure that includes strong earthquakes such as the 7.9 magnitude Wenchuan earthquake in 2008 and the 6.6 magnitude Lushan earthquake in 2013. Based on the U.S. Geological Survey (M ≥ 2.5) earthquake catalogue from 2000 to 2025, this study systematically analyzed the spatio-temporal evolution of seismic activities in this area. We determined the completeness of the seismic magnitude by time periods and drew a spatial B-value distribution map using the maximum likelihood estimation method to reveal its variation characteristics. The analysis is divided into three intervals: 2000–2007 (pre-Wenchuan), 2008–2012 (co- and post-Wenchuan), and 2013–2025 (long-term postseismic stage; the 2008–2025 interval includes an observational and forecast assessment window). Low b values persist in the central and southern parts of the LMSF, indicating that the degree of stress concentration in these two regions is relatively high. After 2008, the b value of the Wenchuan Fault Zone rose briefly. After 2013, the b value gradually declined. This fluctuation confirmed the re-accumulation process of regional stress. The analysis results of the Z-value rate change show that there is obvious stillness in the central fault zone (Z > 2), while there is slight activation in some southern areas of the LMSF (Z ≈ −0.5 to 0). These patterns are roughly consistent with the spatial B-value structure, and our research results also provide diagnostic conclusions for interpreting the long-term seismic activity evolution and stress heterogeneity of the LMSF. Full article

Southeastern Spain is a region of moderate-to-high seismic risk, where reliable seismic event detection is a prerequisite for earthquake early warning systems. This paper presents a seismic event detection pipeline based on the Wavelet Scattering Transform (WST) with a ZNE component-feature ensemble, Principal Component Analysis (PCA), and a Support Vector Machine (SVM), developed for the Valencian Community Seismic Network (SISCOVA) in Spain. The pipeline is evaluated on a local dataset of labeled three-component traces spanning January 2025 through mid-March 2026 and benchmarked against a classical recursive STA/LTA detector and three state-of-the-art pretrained deep learning models evaluated in a zero-shot transfer setting. Under known signal-to-noise ratio conditions, the proposed approach achieves an accuracy and F1-score of 98.82%, outperforming both the STA/LTA baseline and all evaluated deep learning models. Qualitative validation on continuous full-day recordings from the SISCOVA network further confirms its operational viability. These results demonstrate that WST-based feature extraction, combined with classical machine learning, provides an effective and computationally efficient alternative for seismic event detection in local seismic networks. Full article

Carbonate formations host abundant hydrocarbon resources and constitute a key target for current and future petroleum explorations. A massive Paleocene-Eocene carbonate platform system overlies Late Cretaceous Deccan volcanic rocks within the Indus Fan Offshore Basin. Low geophysical exploration maturity and insufficient targeted research on carbonate reef identification and platform evolution hinder hydrocarbon discoveries in this region. Using 2D seismic data, this study employs multiple seismic attribute methods to characterize carbonate reef-related anomalies. An innovative reef identification method based on a weighted superposition of spectrally decomposed amplitude spectra is proposed to delineate reef-prone sedimentary facies and characterize the multi-stage evolutionary patterns of the carbonate platforms. Based on quantitative constraints from seismic reflection and amplitude differences, platform evolution is classified into four clear phases: initial development, platform expansion, gradual decline and platform drowning. The initial development phase shows prominent high-amplitude and low-frequency seismic responses, and intervals with such high-amplitude responses may indicate favorable reservoir potential. Platform margin zones show the most prominent amplitude anomalies and are considered priority exploration targets, suggesting excellent hydrocarbon potential within strata formed during the initial platform stage. This study provides quantitative geophysical support for the stage classification of Paleocene–Eocene carbonate platforms in the Indus Fan Offshore Basin, and offers practical guidance for carbonate reservoir exploration and the prospect evaluation of analogous basins worldwide. Full article

Ferdinandea Island, part of a shallow-water submarine volcanic field, emerged in the Sicily Channel between Italy and Tunisia in July 1831 and was eroded below sea level within months; its submerged remnant forms the shallowest water depth region of Graham Bank. Here, we review nearly two centuries of historical accounts, geological interpretations and geomorphological data analysis and reassess them against high-resolution multibeam bathymetry, sub-bottom profiles (CHIRP) and published multichannel seismic data. The field comprises six volcanic edifices (V1–V6), 100–170 m high, located along structural trends characteristic of the Sicily Channel Rift. V3, the shallowest edifice, is the remnant of Ferdinandea Island formed during the 1831 Surtseyan eruption. Its flat summit, wave-reworked terrace and steep flanks record rapid post-eruptive modification. Historical observations and hydrographic surveys document the destruction of the emergent island and a further ~6 m lowering of its shallowest point between 1883 and 2012–2015; the separate contributions of wave erosion, subsidence and gravitational adjustment cannot be resolved from the available data. The same regional structural framework appears to have governed the distribution of the other volcanic centres, pockmarks, erosional escarpments and mass-transport deposits of the study area. Seventeen pockmarks, up to ~540 m wide and 22 m deep, occur as isolated, clustered and locally aligned depressions; they are associated with subsurface concave-upward reflectors and local water-column acoustic anomalies, consistent with focused fluid escape. Failures of volcanic and sedimentary slopes are widespread, with the largest debris-avalanche deposit covering ~2.2 km². Taken together, these observations indicate that tectonics, volcanism, fluid migration, wave- and bottom-current reworking, and gravitational instability have operated over different timescales to shape Graham Bank. Ferdinandea thus offers a rare historical and geological reference for investigating the rapid construction, degradation and long-term evolution of shallow-water volcanic edifices and highlights the still-open questions regarding the evolution and fate of ephemeral volcanic islands. Full article

Prestressed concrete hybrid-reinforced solid square (PCHSS) piles combine strands and rebars for improved ductility. This study presents large-scale shaking table tests (1:2 scale) on PCHSS pile–superstructure systems embedded in soft and stiff clay, subjected to four ground motions with distinct frequency contents. The experimental program systematically captured the evolution of natural frequencies, damping ratios, dynamic earth pressure distributions, bending moment profiles, curvature ductility demands, and post-test cracking patterns. Results reveal that ground stiffness governs the degradation pathway and energy dissipation mode: soft clay exhibited 37.3% frequency degradation (1.33× that in stiff clay), while stiff clay showed a 101% damping increase (>3× soft clay). Long-period ground motions generated maximum curvature ductility demands and peak bending moments 2–3 times those of short-period records under identical PGA, attributed to near-resonance coupling. Pile–soil interaction transitions from compatible deformation to progressive separation with increasing seismic intensity, with gap spacings of 40–53 mm observed in soft clay. Notably, the code-specified 4D reinforcement zone was found insufficient for soft clay foundations, where crack distributions extended to 4D–7D, warranting an extended zone up to 7D. The findings provide experimental benchmarks for numerical model calibration and offer practical guidance for extending hybrid-reinforced precast piles into moderate-to-high-seismicity regions. Full article

Seismic liquefaction poses a significant threat to infrastructure and human safety, making accurate regional-scale hazard assessment essential for effective disaster mitigation. This study systematically compares simple kriging (SK), ordinary kriging (OK), and sequential Gaussian simulation (SGS) for liquefaction potential mapping using a case study of the Chi-Chi earthquake. Results show that among the eight theoretical semivariogram models, the exponential model was identified as the optimal semivariogram model, showing the best fit and the lowest validation errors. SK and OK yield nearly identical LPI estimates with high accuracy and low computational cost, but oversmooth high-risk zones and underestimate spatial uncertainty. In contrast, SGS captures spatial heterogeneity and extreme values, with variance and coefficient of variation maps revealing higher and more heterogeneous uncertainties, which offers a more comprehensive basis for probabilistic risk assessment. However, these advantages came at a substantially higher computational cost. The choice of method should therefore depend on the engineering objective: kriging for rapid, large-scale trend estimation, and SGS for detailed probabilistic risk evaluation where capturing extreme values and uncertainty is critical. Full article

This paper presents findings from a comprehensive assessment aimed at identifying deep geological storage formations suitable for the secure isolation of chemically active gases, including anthropogenic CO₂. Although Kazakhstan currently lacks operational industrial-scale CO₂ storage sites, high annual emissions exceeding 2 million tonnes are concentrated in its southern region, specifically Almaty city and the surrounding Almaty Region. Despite this pressing need, the precise location, availability, and capacity of potential storage sites in this area remain poorly understood. By synthesizing legacy geological, geophysical, and hydrogeological datasets compiled within the eastern Ili Depression, this study evaluates regional deep saline aquifers for potential CO₂ geological storage under favorable techno-economic conditions. It must be clearly emphasized that this study focuses exclusively on deep groundwater aquifers (saline aquifers). Leveraging historical seismic, drilling, and well-logging data originally acquired for petroleum and water resource exploration, we constrain the stratigraphic architecture and structural framework of prospective storage units. The lithostratigraphic framework of the sedimentary cover in the Ili Basin is established, identifying key reservoir intervals and effective sealing formations. The results indicate that the eastern Ili Depression offers highly favorable conditions for geologic storage, with Permian, Triassic, and Jurassic sedimentary successions reaching thicknesses of up to 1200 m. Reservoir intervals are identified across major stratigraphic units, with potential storage formations accounting for up to 60% of the stratigraphic volume. Specifically, the Miocene–Paleogene and Jurassic intervals host sandstone reservoirs exceeding 10 m in thickness, with porosities reaching up to 30%. Upper Jurassic clayey successions function as effective intraformational seals for Middle Jurassic reservoirs, while Upper Cretaceous clay sequences provide regional caprock integrity for the overlying Neogene–Paleogene sandy intervals. These geological settings satisfy rigorous containment criteria required for secure gas sequestration. These insights into the deep architecture of the Ili Depression elucidate key geological controls governing prospective storage sites, paving the way for future carbon capture and storage (CCS) initiatives in one of Kazakhstan’s most vital economic regions. Full article

A study was performed on the electromagnetic response of the geological medium during the propagation of Rayleigh waves from the 2025 Kamchatka earthquakes (M8.8–7.4) at an epicentral distance of approximately 6000 km. The identities of the coseismic telluric current variations and the propagating Rayleigh wave have been revealed, with their power spectra exhibiting a pronounced quasi-line structure with dominant peaks at 0.04 Hz, 0.054 Hz, and 0.064 Hz. The high correlation of the telluric current response with the Rayleigh wave (r = 0.906, M8.8 and r = 0.83, M7.8) allowed the seismoelectric effect of the second kind to be considered the dominant mechanism for disturbance generation. Electromagnetic signals recorded by the IMS-008 induction sensor showed a lower correlation (r = 0.682), which may be attributed to the shaking of the induction sensor during the passage of the Rayleigh wave, though this does not preclude the presence of a true coseismic signal. Coseismic effects were recorded during the M7.8 and M8.8 earthquakes, but were absent during the M7.4 events. For the first time for the Northern Tien Shan region (at teleseismic distances of approximately 6000 km), key regularities in the generation of the seismoelectric effect during Rayleigh wave propagation have been identified. It is shown that the telluric current response is characterized by a threshold sensitivity to the event magnitude, with the magnitude of induced current variations strictly consistent with the intensity of the seismic wave’s dynamic impact. Utilizing telluric currents as a physical reference for the precise determination of Rayleigh wave arrival times allowed for the refinement of the Rayleigh wave group velocity (3.078–3.093 km/s), reducing calculation uncertainty to 0.5%. Full article

Indonesia is one of the world’s most seismically active countries, experiencing frequent earthquakes that make assessing regional resilience essential for disaster risk reduction. This study dynamically evaluates socioeconomic resilience in 28 regencies/municipalities affected by destructive earthquakes between 2016 and 2022. Resilience was quantified using the Adjusted Mazziotta–Pareto Index (AMPI) at three periods: pre-event (T₀), during the event (T₁), and post-event (T₂). Index changes were interpreted as resistance (Δ₁ = T₁ − T₀), recovery (Δ₂ = T₂ − T₁), and adaptive capacity (Δ₃ = T₂ − T₀). Results show substantial regional differences in resilience trajectories: some areas experienced only minor declines during the earthquake, while others were heavily affected but recovered quickly. Cluster analysis revealed distinct typologies, including consistently high-resilience regions, rapid-recovery regions, and persistently vulnerable regions. These disparities are associated with variation in economic capacity, social vulnerability, labor market conditions, and access to health services. Overall, the findings highlight the value of a multidimensional, time-sensitive approach to measuring socioeconomic resilience. The study advances an AMPI-based temporal measurement framework and offers policy insights for development planning and disaster mitigation. Full article

The basement lithology in the northern South China Sea remains poorly constrained because of the lack of drilling data, which creates major challenges for predicting bedrock buried-hill reservoirs. This study is based on 2D and 3D seismic data, together with gravity and magnetic data, and is constrained by previous studies on the regional tectonic framework and lithologic distribution of the northern South China Sea. We investigated the basement lithologic composition of the XS area, established an integrated gravity–magnetic–seismic interpretation framework for basement lithology, and discussed the possible geological controls on basement lithologic distribution. The results show the following: (1) The basement in the study area is mainly composed of granite intrusive bodies, metamorphic rocks, and volcanic rocks. Granite bodies are characterized by irregular to intrusive seismic geometries, strong double-peak reflections at the upper boundary, and weak-amplitude, medium- to low-frequency internal reflections, reflecting their intrusive characteristics. Metamorphic rocks show diverse external seismic geometries, single-peak or weak reflections at the upper boundary, and medium- to strong-amplitude parallel internal reflections that intersect the upper boundary at high angles. Their gravity and magnetic responses show considerable overlap with those of granitic rocks. Volcanic rocks commonly show mound-shaped or lenticular seismic geometries and medium- to strong-amplitude, moderately continuous internal reflections. Intermediate–mafic volcanic rocks are associated with relatively stronger gravity and magnetic anomaly responses, whereas felsic volcanic rocks generally exhibit weak to moderate gravity and magnetic responses. These characteristics provide an integrated seismic–gravity–magnetic constraint framework for basement lithology interpretation in the South China Sea. (2) Integrated gravity–magnetic–seismic interpretation indicates that, near the present top of the pre-Cenozoic basement in the XS area, granite intrusive bodies are the dominant lithology. Metamorphic rocks mainly occur as discontinuous basement remnants in local structural lows or erosional windows, whereas volcanic rocks are mainly distributed near fault intersections or occur as bead-like bodies along fault zones. (3) The distribution of granite intrusive bodies and metamorphic basement is interpreted to be related to Indosinian–Yanshanian magmatic activity, tectonic deformation, and subsequent denudation. Faults formed during Early Yanshanian compression were later reactivated during the Himalayan period and may have acted as magma conduits, promoting the development of volcanic edifices along fault zones. Full article

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

Automatic fault interpretation is essential for seismic geological modeling; however, fault intersections, noise interference, and topological complexity frequently lead to over-segmentation or under-segmentation. To address these challenges, we propose multi-scale contour constraints Delaunay-based region growing (MC-DBRG), an instance segmentation method for three-dimensional (3D) fault point clouds. This approach effectively extracts individual fault instances from fault probability volumes. The pipeline begins with voxel downsampling and multi-scale feature extraction applied to the fault point cloud. A Gaussian Mixture Model then performs binary classification to delineate explicit and closed fault contour walls. These walls function as physical barriers during the subsequent Delaunay triangulation-based region growing, which initializes from non-contour smooth points. Implementing these constraints guides the growth process and prevents topological adhesion among intersecting faults. To correct over-segmentation caused by data discontinuities in the preliminary results, we introduce a global manifold secondary geometric merging strategy. A macroscopic planar trend constraint is subsequently applied to accurately reassign and backfill contour points and noise. Experimental results indicate that MC-DBRG resolves boundary ambiguity and spatial adhesion within complex intersecting faults. The generated fault models preserve high topological integrity and precise instance labels, establishing a reliable foundation for automated seismic geological modeling. Full article

This study examines the post-earthquake reconstruction framework adopted in the Mt. Etna region, where the ordinances issued by the Extraordinary Commissioner provided the operational structure enabling the integration of technical, geological, and landscape-protection requirements. Geological, geophysical, and geognostic investigations were mandated to characterize local subsurface conditions and ensure that repair or reconstruction works complied with safety standards and regulatory requirements, particularly where retaining walls support buildings, roads, and infrastructure. A distinction was made between traditional dry-stone retaining walls—an essential component of the rural Etnean landscape—and reinforced concrete walls, which are adopted in contexts requiring higher structural performance. Their reconstruction involved differentiated technical approaches aimed at ensuring deformation-compatible behavior and mitigating the effects of permanent ground deformation while preserving the historical and cultural value of dry-stone constructions, recognized as UNESCO intangible heritage. The resulting reconstruction model integrates high-resolution geostructural and geophysical surveys, Active and Capable Fault (ACF) zoning criteria, and performance-based geotechnical design within a unified governance and technical protocol. This approach provides a replicable methodology for the post-seismic reconstruction of retaining walls in areas affected by permanent ground deformation and complex volcano-tectonic settings. Full article