The southern Kamchatka Peninsula lies along the southeastern margin of the Okhotsk microplate; a region identified with high seismic potential. This segment of the megathrust hosted the historic Great Kamchatka earthquake (Mw = 9.0) in 1952, one of the four largest ever instrumentally recorded. On July 29, 2025, an Mw = 8.8 earthquake ruptured a similar portion of the megathrust through shallow reverse faulting, which is characteristic of subduction zones. In this study, we investigate the coseismic slip behavior of this event along the Kuril-Kamchatka subduction zone by directly modeling gravity data from the GOCE satellite mission. Finite-fault models from different data sources indicate that the rupture propagated entirely southwestward. Most of these models showed that deformation was distributed across distinct patches, with the highest slip occurring to the southwest of the epicenter, mainly between 50° and 51° N, coinciding with a low anomaly of the vertical gravity gradient (Tzz). Spectral coherency between a coseismic slip distribution model and Tzz showed a correlation of about 90%. A saddle-point in the Tzz variation at 53° N marks an important seismic barrier that also constrained previous great megathrust earthquakes. The northeastern termination of foreshock and aftershock activity further supports this. Another seismic barrier was inferred at 51° N by comparing Tzz to coseismic slip and to kinematic rupture models. Our results show that the Tzz effectively maps major asperities and barriers, in agreement to the degree of interseimic coupling, as found in previous studies of other great megathrust events around the world. We conclude that the density distribution mapped from satellite GOCE indicates a primary factor controlling seismic segmentation. We also propose the Tzz as a first-order proxy for seismic hazard assessment, as well as for constraining locking and finite-fault models that require a priori information on megathrust structure.
The seismic vulnerability of buried pipelines, affected by multiple factors with significant variations under different conditions, poses challenges for accurate assessment due to differing model applicability and complex multi-factor coupling effects. Using Incremental Dynamic Analysis (IDA), this study verified the accuracy of discrete spring and 3D solid models, then considered factors like soil type, burial depth, wall thickness, internal pressure, and corrosion age. Twenty suitable ground motion records were selected, with the peak ground acceleration (PGA) as the intensity measure (IM) and the maximum axial tensile strain as the damage measure (DM). A probabilistic seismic demand model was established, and the seismic response and vulnerability of buried oil pipelines were studied. Results show 3D solid models are more accurate; pipeline response and failure probability in soft soil are much higher than in hard soil; greater burial depth and wall thickness reduce seismic impact, while higher internal pressure and longer corrosion age weaken seismic performance. This study offers reference for seismic risk assessment and anti-seismic optimization design.
The 2026 magnitude 6.3 Haixi earthquake in Qinghai caused one death and eight injuries. A detailed field survey was carried out immediately after the earthquake by the authors to investigate the damage to buildings and infrastructures in the affected area. In this study, the damage characteristics of the buildings and various infrastructures, such as roads, bridges, towers and chimneys, are summarized and the unexpected damage phenomena which may provide lessons for future research are introduced. A few prominent damage characteristics were identified: (1) The multi-storey RC frame public buildings remained generally intact, whereas non-structural components, such as infill walls, suspended ceilings and facing tiles, were commonly damaged, which limited their immediate post-earthquake use. In contrast, adjacent older low-rise masonry buildings performed surprisingly well, which may be attributed to both the structural properties and the spectral characteristics of the ground motion. (2) Several tall and flexible structures were severely damaged, including mid-height dislocation or complete collapse in some instances. The failure directions of water towers, chimneys, monuments and boundary walls were generally perpendicular to the strike of the fault, indicating a pronounced directional dependence. (3) Damage occurred at bridge unseating-prevention blocks, splayed wing walls and road-bridge transition zones, while longitudinal and transverse cracks, local uplift and signs of liquefaction were found along roads. (4) Continuous rainfall before and after the earthquake, together with seismic shaking, induced or aggravated secondary hazards such as rockfalls and landslides, resulting in cascading disasters that further aggravated road blockages and building damage. These findings offer insights and lessons for seismic damage assessment and disaster mitigation in plateau and mountainous regions, especially for public buildings.
On 3 April 2024, an Mw 7.4 earthquake struck offshore Hualien, eastern Taiwan Island, triggering a localized tsunami with a peak amplitude of 0.8 m at the Su’ao tide gauge. Despite the significant onshore geodetic coverage, the event’s precise seismogenic fault and rupture extent remain elusive due to the complex tectonic setting and the invisible nature of offshore deformation to terrestrial networks. To bridge this gap, we employ a tsunami waveform inversion approach that requires no pre-assumed rupture fault, utilizing Green’s functions computed from a grid of 75-unit Gaussian sources via the JAGURS model. Our inversion reveals a primary sea-surface uplift of ∼2.9 m near the hypocenter, complemented by moderate deformation to the south and northeast. This seafloor displacement model is further validated by InSAR (Interferometric Synthetic Aperture Radar) analysis, which shows onshore vertical displacements exceeding 50 cm near Hualien, consistent with both field surveys and our inverted offshore results. Compared to existing fault models, our inversion-based approach demonstrates better agreement with observed tsunami arrival times and waveforms. With such characteristics of the seafloor deformation, we infer that the primary tsunamigenic source is the west-dipping Takangkou-High Thrust Fault, potentially involving co-seismic rupture along the northern Longitudinal Valley Fault. This study underscores the synergy between tsunami inversion and onland geodetic data in characterizing complex offshore earthquake sources, offering critical insights for seismic and tsunami hazard assessment about nearshore earthquakes.
To investigate activity in the western Circum-Pacific seismic zone, we established the China-Wide Fiber-Optic Seismology Network (CFOSN). This network integrates 14 continuously operating Distributed Acoustic Sensing (DAS) systems from provincial earthquake agencies, universities, and infrastructure management entities, forming an observational framework that covers geologically diverse regions across China. On 28 March 2025, eleven of all online DAS interrogators recorded clear teleseismic signals from the M7.7 Myanmar earthquake and its M 6.7 aftershock. A total of approximately 237.4 km of telecommunication cables were repurposed as DAS arrays that transect plateaus, basins, plains, and coastal zones, spanning rural areas to major cities. Waveform amplitudes decay with increasing epicentral distance, with localized amplification at several DAS arrays. Short-time Fourier transform (STFT) and frequency-wavenumber (-) analyses recover consistent teleseismic patterns across all lines and reveal spectral differences attributable to sedimentary amplification, local geology, and environmental noise. Frequency–time analysis (FTAN) and - retrieve dispersion curves for different surface waves. These observations demonstrate the network’s potential for regional and continental geophysical monitoring. Nevertheless, several limitations remain, including strong site effects, heterogeneous cable-ground coupling, single-component sensitivity with azimuthal bias, limited sensing range per unit, low sensitivity, and instrument noise. Overall, CFOSN offers the potential for a low-cost, wide-coverage, high-resolution model for next-generation geophysical observations, providing a robust dataset for earthquake early warning and Earth-system studies.
To address the complex challenges in seismic wave propagation modeling for coastal and offshore engineering sites, traditional analytical methods based on terrestrial site assumptions and vertical seismic wave incidence are insufficient for accurately capture the fluid-soil coupling effects and oblique wave propagation mechanisms unique to marine sites. This paper aims to establish a theoretical method for seismic motion input method for obliquely incident P waves in a horizontally layered seawater-seabed-bedrock system. Based on the artificial boundary substructure method, a numerical implementation path capable of accurately simulating wave mode conversion and scattering effects at fluid-solid coupling interfaces was established. Through a comparison of theoretical and numerical solutions for typical case studies, the high accuracy of this model in simulating wave propagation in multi-layer media was verified. The research results indicate that, compared to the traditional assumption of vertical incidence, the artificial boundary substructure method proposed in this paper for multi-layer media (seawater-seabed-bedrock) can more accurately capture the dynamic response characteristics of both the surface and deep soil layers in coastal sites. This significantly improves the reliability of seismic response predictions and provides an efficient theoretical tool and technical support for seismic safety assessment of major coastal and offshore engineering under complex marine site conditions.
Existing landslide susceptibility prediction methods often fail to fully account for the spatial heterogeneity of environmental factors such as topography, soil, and vegetation, nor do they accurately reflect the impact of extreme rainfall on landslide susceptibility. To overcome these limitations, this study proposes two innovative methods. First, to address the issue of spatial heterogeneity, a Deep Embedding Clustering (DEC) approach is introduced. DEC utilizes an autoencoder to map environmental factors to a lower-dimensional space, capturing nonlinear relationships between variables and performing clustering in this space. Unlike traditional methods, DEC does not rely on simple distance measures; instead, it jointly optimizes clustering centers and feature representations, enabling more precise regional delineation, which significantly enhances prediction accuracy and adaptability to varying environments. Second, to address the static nature of rainfall thresholds, a mixed distribution modeling strategy is proposed for both non-extreme and extreme rainfall. In this strategy, non-extreme rainfall is modeled using the Gamma distribution to describe cumulative effects, while extreme rainfall is modeled using the Generalized Pareto Distribution (GPD) to model extreme values, with thresholds dynamically determined using the Pickands theorem. Additionally, a Bayesian online parameter updating mechanism is implemented to dynamically adjust distribution parameters, recalibrating the model when real-time rainfall data deviates from historical distributions, significantly reducing response time and improving the model's adaptability to changing rainfall patterns. By combining Deep Embedding Clustering (DEC) and the mixed distribution rainfall threshold model, this study achieves more precise spatial zoning and dynamic rainfall responses, greatly improving prediction accuracy and timeliness. Compared to traditional models relying on uniform thresholds, the experimental results show that landslide density and event numbers have increased from 0.038 events/km2 and 44 events to 0.044 events/km2 and 59 events, respectively, validating the importance of incorporating spatial heterogeneity and distinct rainfall event types in landslide susceptibility prediction.
This study investigates the dynamic response and damage mechanisms of underground structures under explosive impacts. A 3D numerical simulation was conducted to analyze the coupled interaction among the explosive, rock mass, and a concrete circular-arch structure with straight walls. A dynamic explicit finite element model was developed and validated by comparing key physical quantities with those from previous model tests. Based on the validated model, systematic sensitivity analyses were performed to evaluate the effects of explosive charge mass, concrete strength, and reinforcing bar strength on structural dynamic responses. The research findings indicate that variations in energy dissipation pathways within underground structures, induced by different types of equivalent explosives, are the primary factors governing the damage characteristics of such structures. Under the test conditions of this model study, enhancing the concrete and reinforcing steel strength of underground structures can effectively mitigate overall structural deformation. However, solely increasing the strength grades of concrete and steel reinforcement exhibits a significantly diminishing marginal return in improving the blast-resistant performance of underground structures. The research findings elucidate the damage evolution mechanism of underground structures subjected to explosive shock loading, thereby offering theoretical support for optimizing anti-explosion design parameters in protective engineering.
The Three Gorges Reservoir area (TGRA), primarily characterized by hilly and mountainous terrain, has historically been a high-risk and frequent-occurrence area for geological hazards. Therefore, advance planning for geological hazard prevention in the TGRA is fundamental to ensuring long-term geological safety of the reservoir's towns and waterways. In this paper, we systematically analysis the planning, implementation and funding of key projects on geological hazard prevention in the TGRA since 2000. The results reveal that the planning strategies are closely linked with the construction phases of the Three Gorges Project. The master plan formulated before water storage in 2001 covered the second phase (2001-2003) and third phase (2004-2010) of the project construction. The follow-up work plan formulated in 2011 and its 2020 revision corresponded to the initial operation and comprehensive operation phases of the project respectively. Planned projects mainly include engineering treatment for collapse/landslide/perilous rock mass (CLP) , bank collapse/high-cut slope protection, relocation and avoidance, professional monitoring, and community-based monitoring. Particularly, As the geological hazard prevention in the TGRA advanced, the focus gradually shifted away from CLP engineering treatment projects, with the monitoring and early warning projects continuously enhanced. The funding structure also has evolved significantly. This research innovatively constructs a "project-funding-policy-theory" four-dimensional evolutionary analysis framework, reveals the paradigm shift from "engineering-dominated treatment" to "integrated risk management" in large-scale reservoir hazard prevention, and provides a theoretical reference for environmental planning and management in similar areas both domestically and internationally.
The Doppler effect is widely observed and applied in sound and electromagnetic waves, but its use in seismic waves has been relatively limited. Seismometers, however, can record vibration signals generated by moving vehicles and aircraft. In this study, we utilized data from a single seismometer to analyze the Doppler effect of seismic signals generated by moving sources. Through experiments conducted on the Hefei Ring Expressway and Guangzhou Baiyun Airport in China, we captured the Doppler responses of vehicle and aircraft signals. By employing Doppler curve fitting methods, we successfully estimated vehicle speed and lane position, as well as aircraft acceleration, speed, and altitude during takeoff and landing phases. The results indicate that seismic signals can serve as a new monitoring data source, less influenced by visibility and weather conditions, thereby offering a novel approach for traffic monitoring and flight condition assessment.
The Makran Subduction Zone (MSZ) represents one of the most significant yet underexplored tsunamigenic earthquakes sources, posing significant hazard to coastal communities along the Arabian Sea. This study presents the first comprehensive bibliometric analysis of eighty years (1945-2025) research on MSZ tsunamigenic earthquakes, aiming at understanding the evolution, collaboration patterns, and thematic development of this critical domain. This bibliometric analysis was conceived in parallel with, and inspired by, a review paper that we were developing simultaneously on the same topic. A total of 246 publications, extracted from an initial pool of 1,850 indexed records, were subjected to citation, co-authorship, and keyword co-occurrence analyses using VOSviewer. Results revealed a steady increase in research output, reflecting a shift from descriptive focus from geological and seismotectonic studies toward interdisciplinary, data-driven approaches integrating numerical modeling, geodesy, and tsunami risk assessment, with strong international collaboration. These advances reflect the increasing alignment of MSZ research with sustainable disaster preparedness and coastal resilience goals. The findings provide valuable insights for researchers and practitioners, into the intellectual structure, emerging hotspots, and research gaps, thereby supporting future directions that align with sustainable coastal development, disaster risk reduction, and regional resilience. It provides an evidence-based foundation to guide future research directions, strengthen collaborative frameworks, and support sustainable coastal development strategies in the Makran region.
Asymmetric single-pylon cable-stayed bridges typically employ a pylon-girder rigid connection to balance the significant asymmetry in mass and stiffness. However, under strong seismic action, this conventional design leads to severe bending moment concentration in the joint zone, posing a high risk of local damage. To address this critical issue, this study proposes a vertical hinged connection system. This study focuses on an asymmetric single-pylon cable-stayed bridge with a total length of 320 m and a main span of 190 m. Utilizing dynamic time-history analysis, the global seismic responses and the detailed strain behavior in the joint zone under seismic excitation were systematically compared between the two systems, validating the effectiveness of the proposed vertical hinged connection in local damage control. The findings of the study indicate that in scenarios involving combined vertical and longitudinal seismic actions, the conventional rigid connection method gives rise to a significant concentration of bending moment in the joint zone. This is attributable to the effects of pylon offset and girder vertical bending, which collectively result in elevated strain levels and considerable local damage risk. Conversely, the vertical hinged connection effectively releases the girder's rotational degree of freedom about the transverse direction, thereby eliminating bending moment in the joint zone induced by pylon offset and girder vertical bending during earthquakes. This approach has been shown to significantly reduce principal strains in both the girder and the lower pylon segment within the joint area, thereby mitigating the risk of cracking at the girder-pylon joint. The findings provide a valuable reference for the seismic design of pylon-girder restraint systems in asymmetric single-pylon cable-stayed bridges aimed at local damage control.
The seismic hazard in the economically vital Guangdong–Hong Kong–Macao Greater Bay Area (GBA) may be underestimated due to limited constraints on deep crustal structure beneath this intraplate region. Imaging the crust using complementary geophysical parameters is essential for understanding the mechanical state of the lithosphere and its role in earthquake processes. To complement existing regional shear-wave velocity models, we conducted a ∼100-km-long high-resolution magnetotelluric (MT) transect across the western flank of the Pearl River Delta. The resulting resistivity model reveals multiple crustal low-resistivity zones interpreted as fluid-rich or partially molten domains. These conductive anomalies show good spatial correspondence with previously reported low shear-wave velocity features, providing independent validation of the regional seismic structure.Our principal finding is a laterally extensive mid-crustal zone characterized by both low resistivity and low shear-wave velocity near Xinhui, Jiangmen. This anomalous body forms a mechanically weak domain embedded beneath a comparatively rigid upper crust, indicating partial mechanical decoupling between the upper and middle crust. Such a structure does not directly host earthquake rupture but may influence the mechanical environment of upper-crustal faults by facilitating stress redistribution and strain localization. These results suggest that deep crustal rheological heterogeneity plays an important role in modulating intraplate seismicity in the GBA and highlight the value of integrated MT and seismic imaging for seismic hazard assessment in continental interior and marginal regions.
The July 29 2025 Mw 8.8 Kamchatka earthquake ruptured the plate interface off the east coast of the Kamchatka Peninsula along the Kuril-Kamchatka subduction zone and generated tsunamis across the Pacific Ocean, followed by volcanic eruptions in Kamchatka. The mainshock was preceded by an energetic foreshock sequence that began with a Mw 7.4 event on July 20 2025, located 40 km northeast of the mainshock hypocenter. However, the physical mechanisms connecting the foreshock to the mainshock are not completely clear. In this study, we present a detailed seismological and geodetic analysis of the sequence by investigating the rupture characteristics of the Mw 8.8 mainshock, the spatiotemporal evolution of the foreshock and early aftershock sequence, and the processes driving their interaction. Teleseismic back projection reveals that the mainshock ruptured predominantly toward the southwest with a total source duration of ∼220 s. The Mw 7.4 foreshock was accompanied by afterslip along the plate interface, which likely drove an expanding aftershock of its own and eventually triggered the mainshock nucleation. This event also shows anomalously high aftershock productivity relative to other M7+ events before and after the mainshock, indicating an elevated likelihood of triggering a larger earthquake. We also identify possible segmentation of the megathrust rupture zone along the Kuril-Kamchatka subduction zone that is separated by higher topography in the upper plate. These results provide new insight into the physical mechanisms of foreshocks and segmentation of mainshock ruptures along major subduction zones, with direct implications for short-term forecasting and seismic hazard assessment of megathrust earthquakes in this and other regions.
Numerous past moderate-to-strong earthquakes have induced soil liquefaction, leading to severe structural damage in many locations around the world, including in the Aceh Province of Indonesia. This paper aims to assess and map the soil liquefaction potential for the city of Meulaboh, Indonesia, by integrating probabilistic seismic hazard analysis (PSHA) and site response analysis into liquefaction-induced ground settlement using in-situ test data involving the quasi-static cone penetration test (q-CPT). The novelty of this study lies in integrating PSHA with site response analysis to enhance the liquefaction potential assessment. The adopted method in the present study is outlined as follows. Firstly, PSHA was carried out to quantify the bedrock seismic ground motion, i.e., bedrock peak ground acceleration, in a location by considering all possible seismic occurrences within a certain period. Secondly, to obtain the most representative soil peak ground acceleration, site response analysis was performed using the bedrock peak ground acceleration of PSHA and sub-surface models developed from various sub-surface site investigation methods, i.e., quasi-static cone penetration test (q-CPT), boreholes, and microtremors measurements, across the study area. Finally, a liquefaction assessment was carried out by means of the ground settlements, liquefaction potential index (LPI), and liquefaction severity number (LSN) by considering various seismic hazard scenarios of 10% and 2% probability of exceedance (PoE). Further liquefaction assessments were also carried out in the case of the historical M9.1 Sumatra-Andaman earthquake and the M7.5 earthquake scenarios. These scenarios represent the most common and critical seismic magnitude for evaluating liquefaction hazard potential. The worst-case results of the liquefaction assessment in the present study suggests that the estimated ground settlement due to soil liquefaction within the study area (city of Meulaboh) can be up to ∼309mm, LPI is classified as very high hazard (LPI>15), and LSN is categorized as moderate to severe (20<LSN≤30). Based on the spatial distribution analysis by means of maps for all seismic event scenarios, the main vulnerable part of the city of Meulaboh is on the southern tip and along the coastal areas.
This study integrates the Extended Spatial Auto-Correlation (ESPAC) method, the Multi-Window Stacking Method (MWSM), and half-wavelength inversion imaging to construct a microtremor survey methodology to address the exploration requirements for deep fractured geothermal resources. The system enhances the detection accuracy of deep geothermal reservoir structures through synergistic innovation in core algorithms and standardized field procedures. The methodological innovation is demonstrated by: employing the MWSM strategy to overcome the limitations of traditional single time-window processing, utilizing a dual time-window cooperative mechanism to achieve an optimal balance between high-frequency noise resistance in shallow sections and low-frequency convergence in deep sections, thereby significantly enhancing full-band signal continuity; and effectively suppressing complex environmental interference by combining standardized techniques such as cross-shaped array configuration, precise station positioning, and rigorous sensor coupling. In the application to a geothermal target area in Xinyu, Jiangxi Province, the system identified multiple heat-controlling faults and several target low-velocity anomaly zones. Key geological features revealed include deep low-velocity fault channels and medium-shallow vuggy limestone geothermal reservoir cores. Typical targets were strictly verified by drilling: the prediction error for the top boundary depth of the geothermal reservoir was less than 3%; the locations of fault zones and the spatial distribution of the reservoirs showed high consistency with the velocity profiles. Drilling revealed that the vertical control depth of the fault system reaches nearly a kilometer, confirming that the three-dimensional delineation capability of this method for reservoir structures and permeable channels meets engineering accuracy requirements. The research results provide reliable technical support for the exploration of deep fractured geothermal resources.
This study proposes a method for determining earthquake focal depths by combining the sPn phase with the waveform cross-correlation technique, based on waveform data recorded by the Fujian Seismic Network from the 2024 M 7.3 Hualien offshore earthquake and the 2025 M 6.2 Tainan earthquake. The Pn phase onset was precisely aligned using waveform cross-correlation, and the arrival time difference (Delta t) between the sPn and Pn phases was extracted via a sliding time-window correlation method. The focal depths were derived using a layered velocity model for the Taiwan region. Results show that the calculated focal depth for the Hualien earthquake is 23.1 km (Delta t = 6.9 s), with a relative error of 2.7% compared to the official result (22.5 km) from the Central Weather Administration of Taiwan. For the Tainan earthquake, the depth is 17.9 km (Delta t = 6.1 s), with a relative error of 13.3%. In this study, we show that a cross-correlation threshold of 0.8 and a bandpass filtering of 0.1-0.3 Hz are efficient to suppress noise and significantly improve depth accuracy for shallow earthquakes with depth <30 km. Compared to traditional travel-time location methods, this approach exhibits superior noise resistance and computational efficiency. Future work will focus on optimizing 3D velocity structures, integrating multiple phases, and applying deep learning techniques such as convolutional neural networks, aiming to improve the results in a more reliable and automatic way, and to provide efficient support on earthquake emergency response.
The 2018 Sulawesi Earthquake induced extensive liquefaction cases across several sites in Indonesia, resulting in large-scale flow slide at Balaroa, Jono oge, and Petobo. This unprecedented ground failure phenomenon caused severe damage and losses. Liquefaction assessment in Indonesia is commonly based on simplified methods using the standard penetration test (SPT) to estimate the liquefaction potential index (LPI). However, these methods do not account for seismic duration and time effects, nor do they capture the excess pore water pressure ratio (ru) or changes in effective stress of the ground. This research investigated the liquefaction index ratio using simplified methods and dynamic analysis which considers earthquake motion input from the deconvolution process performed by the DEEPSOIL program. Furthermore, the effective stress decreasing ratio (ESDR) analysis was conducted using numerical analysis through LIQCA 2D as a fully coupled method of two-phase theory. The analysis employed the elastoplastic constitutive model with horizontally layered ground, utilizing finite element simulation. The liquefied layer from the time history was examined as part of the back analysis of earthquake induce-liquefaction, yielding liquefaction resistance index (LRI) from 9 boreholes. Even though there are differences in results due to the scheme and basic concepts of analysis, the outputs showed a strong connection index for examining the maximum and minimum index ratios. ESDR analysis provided the LRI with strong interconnection dynamic parameters, such as the small value ru which did not reach the 0.9 value that correlated with lower ESDR. The highest ESDR value from each layer did not always produce the highest LRI. This research highlights the significant contributions of detailed and complex dynamic methods in providing realistic liquefaction simulations, while also emphasizing that simplified methods can serve as standard practice for engineers in Indonesia. Both approaches are adequate models for assessing the liquefaction ratio value.
