Mining seismic activity is an important factor in assessing the risk of rockbursts in coal mines. In order to predict the mining seismic activity, this study uses qualitative and quantitative analysis methods to explore the correlation between passive velocity tomography and future seismic activity in mines. For qualitative analysis, we compared the similarity between the areas with high longitudinal wave (P-wave) velocity and those with future high seismic activity. 87.5% of cases showed moderate to strong correlation. For quantitative analysis, we calculated the percentage of seismic events with different energy magnitudes, which were located in the velocity area where the velocity anomaly coefficient An exceeds thresholds of 5%, 15%, and 25%, respectively. In the velocity area where An exceeds 5%, it has good prediction efficiency for various energy levels of seismic events, with an average prediction efficiency of over 80%. A baseline model was used to show that the seismicity prediction performance of velocity tomography is superior to random prediction. Therefore, the results have demonstrated the effectiveness of using velocity tomography to predict and indicate areas where future seismic activities are likely to occur. This study provides significant potential for evaluating and predicting the risk of rockburst hazard in deep coal mines.
The seismic response of terrain sites has long been a hot topic in the field of geophysics and earthquake engineering over decades, which plays a critical role in evaluating the seismic safety of major engineering in mountain areas. In current practice, rocky mountain structures are often treated as a homogeneous body for the simulation of seismic wave propagation, with only the topographic effects taken into account. However, the in-situ stress field can introduce spatial heterogeneity in wave velocity in the hilly body, which may have a significant influence on the seismic wave propagation. In this study, a three-dimensional (3-D) finite element model of a homogeneous Gaussian-shaped hill was first constructed and validated against existing simulations using the boundary element method. Then, an empirical model for the hilly body with shear wave velocity varying with depth in gradients is established based on the results of laboratory tests from the literature. Finally, with the validated model and the empirical relationship, the seismic wave propagation of the 3-D Gaussian-shaped rocky hilly body with gradient shear wave velocity was investigated numerically via the finite element method. The results show that: (1) The gradient shear wave velocity structure of hilly body can significantly influence the seismic wave propagation and alter the spatial distribution of seismic motion near the hilly surface; (2) As the gradient of shear wave velocity structure intensifies, the amplification of surface ground motion on hill generally increases, accompanied by a shift of the transfer function toward lower frequencies; (3) For the complex site effects of rocky hilly body, there exists a complicated interaction effect between the topography and the gradient shear wave velocity structure.
This study presents a detailed seismic fragility and collapse performance assessment of geometrically irregular continuous reinforced concrete rigid-frame (CRCR) bridges based on a representative bridge in Iran. A regular configuration was first established as the reference, after which a systematic set of bridge models was generated by varying the span-length ratio, pier-height ratio, and pier skew angle to investigate their individual and combined effects on seismic response. Detailed three-dimensional nonlinear finite element models were developed in OpenSees and analyzed under a comprehensive set of far-field and near-field earthquake ground motions. Seismic fragility curves were constructed based on pier drift demand corresponding to four damage states ranging from minor damage to collapse, defined by the attainment of the complete damage state. The results indicate that geometric irregularities significantly amplify seismic vulnerability, particularly at higher damage states. Across a range of span-length ratios, bridges with pronounced pier-height irregularity exhibit up to 50-60% higher probabilities of exceeding severe damage at the same intensity level compared to the regular configuration, while the median seismic intensity associated with collapse is reduced by approximately 55% in highly irregular cases. Among the investigated parameters, pier-height irregularity was identified as the most influential factor governing fragility and collapse behavior, followed by pier skewness, whereas span-length irregularity showed a comparatively smaller effect. The resulting fragility functions and collapse metrics provide quantitative insight into the seismic performance of CRCR bridges and support fragility-based assessment and performance-based seismic design in earthquake-prone regions.
Seismic risk assessment is a probabilistic approach that evaluates the likelihood of earthquake occurrence, structural response, expected damage levels, economic losses, and potential casualties by incorporating the inherent uncertainties associated with seismic hazards and urban building characteristics. The primary objective of this study is to quantify and spatially characterize the distribution of damage states at the urban scale. Buildings were classified according to their structural system, age, and number of stories. The structures were initially modeled, analyzed, and designed in ETABS, and the beam and column section properties were extracted for each structural type. Finite element models were subsequently developed in OpenSees, and Incremental Dynamic Analysis, IDA, was performed to evaluate the seismic performance of building groups and large-scale seismic risk. The application of this approach to urban-scale seismic risk evaluation distinguishes this research from similar previous investigations. Given the considerable number of models, the extensive dataset, and the necessity for updating results under varying input conditions, a Bayesian Probabilistic Network was employed. In addition, GIS-based mapping was used to present the findings, including the exceedance probabilities of different damage states and the spatial distribution of collapse probability. The outcomes of this study identify areas that may exhibit relatively higher seismic vulnerability, emphasizing the potential need for targeted retrofitting strategies or, enhanced preparedness for post-earthquake emergency response and rescue operations.
Since the fracture properties and failure modes of concrete are deeply rate-dependent, changes in crack resistance and failure mechanism of concrete, under seismic strain rates, can provide critical insights for structural safety withstanding seismic load. In this study, the dynamic fracture characteristics and micro-mechanisms of concrete under a wide of strain rates range from the static to the seismic (10- 6s- 1~ 10-2s- 1) were explored using three-point bending (TPB) tests combined with Acoustic Emission (AE) monitoring. The results reveal a significant positive correlation between strain rate and mechanical performance. As the strain rate increases, the peak load increases by up to 37.1%, and the fracture energy rises by up to 36.7%, demonstrating a distinct pseudo-strengthening effect. Microscopically, the failure mechanism transitions from ductile interfacial cracking, where cracks deflect along the interface transition zone (ITZ), to brittle transgranular cracking, where aggregates are fractured directly. AE analysis further indicates a shift in the dominant fracture mode from Mode I (tensile) to Mode II (shear), with the proportion of shear cracks increasing from 16.2% to 53.8%. In addition, the spatial distribution of AE events becomes highly concentrated near the pre-crack tip, signifying a transition to brittle failure. These findings provide critical insights into the dynamic fracture mechanisms of quasi-brittle materials, highlighting the inherent trade-off between fracture strength enhancement and ductility reduction under rapid loading conditions, which is essential for seismic engineering and structural safety assessments.
As the scale and complexity of underground structures continue to increase, seismic dynamic analysis places higher demands on numerical computing capacity. In this study, a seismic time-history analysis framework based on high-performance parallel computing is adopted, and a refined three-dimensional finite element model with more than five million elements is established to assess the feasibility of large-scale three-dimensional seismic analysis for complex underground structures. In addition, the dynamic response characteristics of a fully prefabricated underground metro station under E2-level earthquake excitation are systematically analysed. The displacement and stress responses of the soil-station system exhibit pronounced spatial non-uniformity, with high-response regions mainly distributed in the lower part of the model, along the soil-structure interface, and at structural geometric transitions and connection zones. Statistical results from representative monitoring points indicate that the locations of peak acceleration and peak displacement do not fully coincide. Further analysis shows that Kobe-wave input mainly amplifies the response without changing the dominant system-level response pattern, whereas changes in CHC joint stiffness primarily affect local response levels and the distribution of high-response regions. Taken together, these findings suggest that, with appropriate modelling and solution strategies, large-scale three-dimensional numerical simulations can effectively characterise the system-level dynamic response of fully prefabricated underground metro stations and provide a practical basis for the seismic assessment of complex underground structures.
Carbonate buildups host nearly 40-60% of the world's conventional hydrocarbon reserves, yet their recognition on seismic data remains difficult due to morphological similarity with volcanic edifices, erosional remnants, and tectonic highs. Existing workflows for isolated carbonate buildup (ICB) detection formalize criteria based on regional context, morphology, and internal geometry, but they were largely developed for long-lived, tectonically stable settings and are less effective in geologically complex basins. In the Pannonian Basin, carbonate growth was short-lived, syn-tectonic, and modified by rapid burial and diagenesis, producing smaller and less seismically expressive buildups. A modified, more quantitative approach is therefore required. We apply a refined ICB detection workflow to 3D seismic data from the Badenian (Middle Miocene) succession of the Pannonian Basin, Hungary. The modification eliminates non-essential criteria and introduces new diagnostics, including integrated seismic attributes (instantaneous amplitude, phase, pseudo-relief), crossline and inline consistency, and time-slice signatures. Horizon flattening, calibrated with well logs, cores, and calcareous nannoplankton biostratigraphy, enabled robust interpretation of carbonate morphology and platform evolution. Fifteen candidate ICBs were identified and ranked probabilistically: four probable (> 55%), six possible (45-55%), and five disregarded (< 45%), yielding a mean probability of success of 41% and approximately six high-potential prospects. Biostratigraphic evidence independently confirms a rapid drowning event, marked by subsidence-driven deepening from ~ 30 m to ~ 200 m and a transition to open-marine conditions. This attribute-driven, probabilistic workflow reduces interpretive subjectivity and offers a transferable methodology for predictive reservoir characterization in the Central Paratethys and comparable basins worldwide.
Understanding failed volcanic eruptions is key to mapping magma plumbing and forecasting hazards. Faults and fractures guide magma, but their mechanisms remain unclear due to the lack of precise earthquake locations and limited 3-D fault mapping in volcanic regions. The triple-junction setting of the Azores Archipelago, where volcanic systems and seismogenic faults coexist, offers a natural laboratory to study fault-magma interactions. We analysed ~18,000 earthquakes relocated to high precision using onshore and ocean-bottom seismometers, combined with geodetic data and seismic autocorrelation imaging, during a failed 2022 eruption on São Jorge Island. A magmatic dike ascended rapidly and mostly aseismically from the upper mantle, intruding a crustal fault before stalling ~1,600 m below the surface. Seismicity indicates that magma branching and lateral fluid escape along the fault triggered an intense, months-long swarm with rotated focal mechanisms. This study demonstrates the dual role of faults in facilitating and arresting magma ascent.
To meet the demands of high-rise buildings for long-span spatial layout, low-carbon design and energy conservation, and to break through the application limitations of reinforced concrete open-web sandwich slab structures in high-rise buildings, this study proposes a structure similar to the box-type structure, namely the reinforced concrete open-web sandwich slab-column (RCOSSC) structure. Presently, there is insufficient research evidence to verify whether the RCOSSC can satisfy the overall seismic performance requirements of buildings. To address this issue, this paper verifies the seismic performance of the material and structure through scaled structural tests and multi-software modeling verification. Additionally, the damage resistance of the structure and material is validated via both experimental and simulation methods. Through comparative modeling analysis, the RCOSSC structure maintains its integrity under rare earthquakes, with the inter-story drift angle not exceeding the collapse limit. Engineering simulations confirm that it meets the Grade C high-performance seismic standard, remaining elastic under frequent earthquakes, avoiding collapse under rare earthquakes, and featuring controllable damage. This study provides an industrialized and green structural solution for high-rise long-span buildings.
The subducting cold oceanic plates (slabs) exhibit two paradoxical deformation behaviors: deep seismicity and rheological weakening within the mantle transition zone (MTZ, ~400-700 km depths). Although the transformation of metastable olivine wedge (MOW)1,2 in cold slabs has been proposed as a possible trigger for both behaviors3-10, direct experimental evidence remains limited to understand the processes linking them. Here we report experimental results on the transformation-deformation coupling at MTZ pressures (~20 GPa). Ringwoodite is produced as nano-polycrystalline lamellae (NPL) under uniaxial stress. Thin NPL trigger unstable slips with coseismic stress drops by grain-size sensitive creep coupled with thermal instability at ~760-860 °C. Thickening of NPL at ~950-1,330 °C stabilizes the deformation with enhancing the transformation utilizing their incoherent nature. Thus, the formation of NPL and their grain-size sensitive creep play key roles in temperature-dependent transformation-deformation coupling, which explains both deep seismicity near the MOW and rheological weakening outside the MOW.
Buried steel pipelines serve as core infrastructure for oil and gas transportation. Their corrosion-fault coupling failure under seismic fault activity poses a severe threat to energy security. The present study focuses on an X52 pipeline. The establishment of a finite element model of an internally corroded pipeline crossing a normal fault is based on the ABAQUS finite element software. By comparing the strain responses of corrosion-free and corrosion-defective pipelines, the failure mechanism under the coupled action of normal faults and corrosion is revealed. Through contrasting the failure modes and corrosion locations of reverse-faulted pipelines, the most vulnerable position of corrosion-affected pipelines under normal faulting is verified. Additionally, the study analyzes the influence of stepwise corrosion-characterized by the simultaneous evolution of three parameters: corrosion depth (h/t), corrosion width (w), and corrosion length (l)-under positive faulting on the strain behavior and failure mechanisms of pipelines. The results indicate that local corrosion defects significantly intensify the concentration of compressive strain in the pipeline, triggering local buckling, thereby weakening the pipeline's overall deformation capacity and stability. Compared with tensile failure, normal fault action is more likely to cause compressive failure of the pipeline. The positioning of the corrosion defect at the peak compressive strain region on the pipe crown, consistent with the worst-case principle, can facilitate the accurate revelation of the pipeline failure mechanism under normal fault action. This, in turn, provides a basis for the optimisation of the pipeline's anti-buckling design. Escalation in corrosion stage expedites the deterioration of the pipeline's mechanical performance, evidenced by an earlier onset and more accelerated progression of local buckling, consequently diminishing the pipeline's capacity to resist fault displacements. The present study reveals the critical influence of more realistic corrosion forms and fault coupling effects on pipeline failure behavior, providing theoretical support for the safety assessment and seismic design of corroded pipelines in practical engineering.
Deep-derived carbon dioxide (CO2) degassing is a globally important process linking crust-mantle fluid transport with atmospheric carbon budgets. Matched Field Processing-Bartlett Beamformer (MFP-BB) method offers a seismic approach for detecting tremor signals generated by these degassing centers (mofette). Its principle relies on comparing recorded wavefields with modeled replicas to identify the most likely source locations. This study applies the MFP-BB technique to dense-array seismic noise data from three key mofette areas in the Cheb Basin, western Eger Rift-Bublák, Hartoušov, and Soos. We combine field observations with numerical simulations to evaluate the method's performance. Synthetic tests with interfering noise-embedded sources (SNR = 5 dB) demonstrate that accurate localization is achievable with appropriate frequency selection, and that even 20% perturbations in the velocity model introduce only minor degradation. Field data were processed through segmentation, noise filtering, and spectral analysis to determine persistent frequency bands used in the algorithm. Across all sites, MFP-BB energy concentrates near the surface, coinciding with known mofette fields and CO2 discharge zones. These shallow anomalies reflect microtremors generated as ascending CO2 interacts with groundwater and unconsolidated sediments; additional, weaker anomalies at depths < 200 m may also represent active gas migration.
Understanding how stress and strength conditions evolve before and after large earthquakes remains a fundamental challenge in seismology. Here, we introduce an observationally grounded metric-the ratio of the summed moment tensor to scalar seismic moment (Mstk/M₀)-to track temporal changes in deformation behavior surrounding earthquake faults. Using high-resolution focal mechanism datasets, we analyze two well-instrumented sequences with M6-class foreshocks followed by M7-class mainshocks: the 2016 Kumamoto and 2019 Ridgecrest events. We find that Mstk/M₀ remains elevated after M6-class foreshocks but decreases sharply after M7-class mainshocks, indicating a transition toward a more heterogeneous deformation state. To evaluate broader applicability, we examined nine inland M6-M7 earthquake sequences in Japan (2000-2020). Among ten events that exhibited high Mstk/M₀ during foreshock activity, five maintained high values after the M6-class event, and three of these were subsequently followed by even larger earthquakes. In contrast, all other sequences not followed by larger events showed clear decreases in Mstk/M₀ after the initial large earthquake. These observations suggest that sustained high Mstk/M₀ after an M6-class earthquake may indicate conditions favorable for continued rupture growth, whereas decreases may reflect reduced likelihood of further large rupture. Relationships between Mstk/M₀ and inelastic strain rate further support a physical interpretation linking deformation consistency with the ambient stress field to the potential for large earthquake occurrence. Monitoring Mstk/M₀ in the immediate aftermath of large earthquakes may therefore provide useful information for assessing whether an even larger event is likely to follow.
Large earthquakes commonly generate surface rupture accompanied by both localized on-fault slip and spatially distributed off-fault deformation. Capturing both components is essential for understanding rupture processes and improving earthquake hazard assessment, yet field mapping alone often fails to fully document diffuse deformation. Here we evaluate the applicability of high-resolution Korea Multi-Purpose Satellite (KOMPSAT)-3 and -3A optical imagery for mapping near-field co-seismic deformation using sub-pixel optical image correlation (OIC), through two case-study areas affected by the 6 February 2023 Kahramanmaraş, Türkiye, earthquake sequence. We processed pre- and post-event stereo-mode KOMPSAT imagery using a MicMac-based workflow to generate orthorectified products and displacement fields, and compared the results with published Sentinel-2 OIC products and independent airborne Light Detection and Ranging (LiDAR) measurements. In the Hatay Airport area, KOMPSAT-3/3A OIC recovered a displacement pattern consistent with Sentinel-2, indicating ~5 m of relative motion across the fault, while the ~1 m effective spatial resolution enabled identification of localized infrastructure offsets (runway displacement) that were not detectable in 10 m Sentinel-2 imagery. In the Elbistan near-epicenter area, KOMPSAT-3/3A OIC resolved block motions of ~6 m and ~2 m in opposing directions. Swath profile analysis indicates an average on-fault slip of 6.8 m, whereas the total slip including distributed deformation reaches 9.3 m, implying that approximately 27% of the deformation is accommodated off-fault. Airborne LiDAR mapping provides an independent benchmark, with on-fault net slip of ~6.13 m and horizontal slip of 5.57 ± 1.40 m, consistent with the KOMPSAT-derived on-fault estimates and supporting the quantitative validity of the OIC results. However, the rupture geometry inferred from OIC is simpler than LiDAR-derived mapping, and absolute geolocation uncertainty remains a limiting factor with a post-correction Root Mean Square Error (RMSE) of 10.25 m and Circular Error with 90% Confidence (CE90) of 11.34 m, requiring cautious interpretation of absolute displacement magnitudes. Overall, our results demonstrate that KOMPSAT-3/3A imagery can serve as an effective resource for rapid rupture mapping and quantifying both on-fault and distributed deformation, while highlighting key requirements for improving geolocation control and integrating complementary datasets for robust three-dimensional deformation assessment.
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Coastal development is rapidly expanding worldwide, and seismic anomalies observed in shallow-water environments provide valuable information for drilling hazard assessment and understanding geological processes. However, these anomalies are typically small in scale and are often obscured by dominant signals, making their interpretation challenging. In this study, we apply an integrated workflow that combines ultra-high-resolution (UHR) 3D seismic acquisition with localized rank reduction-based 3D diffraction imaging to enhance the detection and analysis of seismic anomalies in shallow-water settings. The UHR acquisition improves spatial resolution for detecting small-scale subsurface features, while the diffraction imaging suppresses dominant reflection energy and enhances diffraction responses associated with localized subsurface heterogeneities. The proposed workflow was applied to a data that is obtained from a study site in Yeongil Bay, Korea, producing a high-resolution 3D diffraction cube. In the resulting diffraction cube, dominant linear signals such as reflections, secondary bubbles, and multiples were suppressed, allowing channel and polka-dot anomalies to be more clearly delineated and facilitating the analysis of small-scale anomalies that are often obscured by dominant signals in conventional seismic data. These results demonstrate that the integration of UHR 3D seismic acquisition and diffraction imaging provides an effective approach for the characterization of small-scale seismic anomalies in shallow coastal environments.
This study presents an integrated static reservoir characterization of the Upper Cretaceous Bahariya Formation in the Berenice Field, North Western Desert, Egypt. A multidisciplinary workflow combining geological, geophysical, and petrophysical techniques was applied to minimize subsurface uncertainty and enhance hydrocarbon prediction. Seismic interpretation established the structural framework and fault geometries controlling reservoir distribution. A synthetic seismogram was generated to achieve precise well-to-seismic ties, improving the correlation between log-derived parameters and seismic reflectors. Seismic attributes, including variance, dip angle, and dip azimuth, were analyzed to delineate subtle structural and stratigraphic features that are not apparent in conventional seismic data. Petrophysical evaluation from well logs quantified key reservoir properties such as porosity, permeability, and hydrocarbon saturation, forming the foundation for static modeling. Structural and property modeling were integrated to construct a realistic three-dimensional reservoir framework and to distribute petrophysical parameters across the grid, improving the understanding of lateral and vertical heterogeneity. Facies modeling further identified sweet facies and potential new volumetric targets, while fault seal analysis evaluated the sealing capacity of major fault systems and their role in hydrocarbon entrapment. Volumetric calculations provided reliable reserve estimates, and uncertainty analysis was applied throughout the workflow to assess data sensitivity and ensure dependable interpretations. This integrated approach enhances confidence in reservoir characterization and provides a Robust foundation for future exploration and development of the Bahariya reservoir in the Berenice Field.