Timely and accurate estimation of earthquake moment magnitude (Mw) is crucial for damage assessment and emergency response. However, obtaining reliable Mw estimates within approximately 10 min of origin time remains challenging. In this study, we present a novel and robust algorithm for Mw estimation of moderate-to-large earthquakes using regional to teleseismic records. The method was applied to 22 earthquakes (Mw >= 6:5, depth <= 60 km) in western China from 2008 to 2023. Magnitude estimates were obtained within similar to 6 to 11 min after origin time and agree with U.S. Geological Survey values, with a standard deviation of similar to 0.1. The estimates remain robust and stable despite variations in the number and spatial distribution of contributing stations. The algorithm mitigates contamination from reflected phases in regional data and uneven station distribution by employing adaptive time windows and spatial averaging of P-wave amplitudes in azimuth and take-off angle grids. Backprojection yields robust estimates of source durations even with relatively sparse seismic array coverage. However, larger events may require denser station spacing and wider apertures to suppress interfering phases in regional to teleseismic waveforms. Comparative analysis with widely used magnitude scales, such as broadband surface-and body-wave magnitude scales, further confirms the method's stability, demonstrating its potential as a rapid, reliable complement to existing real-time magnitude estimation techniques.

The spatial distribution and temporal evolution of early aftershocks provide valuable insights into understanding the stress transfer process following large mainshocks. Unfortunately, for poorly instrumented regions, due to the sparsity of seismic monitoring stations, and the difficulty in early aftershock detection, the early aftershock catalogs generally have relatively high magnitudes of completeness and large location uncertainties, which prevents accurate depiction of the spatiotemporal evolution of early aftershocks. The 2025 Mw 7.1 Dingri, southern Tibet, earthquake occurred in Dingri County, Rikaze City, the Tibet Autonomous region, China. Field investigations, together with finite-fault inversion and aftershock observations, suggest complex fault structure around the mainshock epicenter. We applied a matched-filter technique to detect early aftershocks following the Dingri earthquake. Using 3224 well-relocated aftershocks as templates, we scanned through continuous data of both permanent and temporary seismic stations within the first similar to 3 days. Compared to 1399 aftershocks and a magnitude of completeness similar to 2.5 reported by the China Earthquake Networks Center, 7179 aftershocks were detected, corresponding to fivefold more earthquakes. The newly detected catalog depicted the main fault geometry and highlighted the spatial variation of the early aftershock distribution.

Rapid constraints on earthquake rupture geometry and shaking intensity are critical for early hazard assessment, but remain difficult to obtain in the first tens of minutes after large earthquakes, particularly in regions with sparse seismic instrumentation. Here we present a globally scalable framework that combines real-time dense-array seismic observations, high-frequency (0.5–10 Hz) multi-array back-projection, known fault geometries, global site-condition models (Vs30), and empirical ground-motion prediction equations to derive rupture extent and physically consistent seismic-intensity fields within ~30 min of origin time. Applications to the 2025 Mw 7.7 Myanmar strike-slip earthquake and a separate Mw 8.8 Kamchatka megathrust event recover rupture dimensions across contrasting tectonic settings that are consistent with InSAR measurements, early aftershock distributions, and macroseismic observations typically available only days later. Because the framework relies only on existing global seismic networks, it enables rapid impact characterization without dense near-source observations. By bridging rapid rupture imaging and physics-informed shaking assessment, this framework represents a methodological advance in global earthquake disaster science, enabling actionable impact estimates within the critical early response window and offering a scalable pathway to reduce seismic losses across vulnerable and under-instrumented regions worldwide.

Misclassifying anthropogenic explosions as natural earthquakes contaminates seismic catalogs, distorts b-value estimates, and undermines foreshock–aftershock discrimination—compromising the reliability of seismic hazard forecasting. Conventional methods suffer from two core limitations: they either process each seismic trace independently and ignore multi-station physical correlations within a single event, or rely on heuristic aggregation rules such as majority voting that cannot adapt to epicentral-distance-dependent signal degradation and fail to correct erroneous single-trace predictions. This work proposes a dual-stage three-branch convolutional neural network for event-level binary discrimination between natural earthquakes and anthropogenic explosions, integrating raw waveforms, time–frequency spectrograms, and numerical physical features. The framework advances the field in three respects. Our framework couples trace-level feature extraction with event-level decision aggregation through a dual-stage end-to-end training paradigm. For multi-station fusion, we developed a self-supervised quality-aware attention mechanism that weights traces by their prediction confidence alone, removing the need for ground-truth quality labels. We further demonstrated robust out-of-distribution generalization across geologically independent datasets, from hard-rock underground quarry blasts to unconsolidated-sediment surface military explosions.The first stage learns intrinsic source-mechanism features via three parallel branches (1D-CNN, 2D-CNN, and a fully connected branch), while the second applies a quality-aware attention module to dynamically upweight reliable records and suppress ambiguous ones. This hierarchical design bridges single-station feature extraction to multi-station evidence aggregation, and end-to-end event-level training further allows encoders to capture physically meaningful, distance-varying seismic signatures, improving far-field robustness. Evaluated on a balanced ComCat test set (865 earthquakes, 865 explosions), the event-level model achieves 96.41% accuracy, 98.08% precision, 94.68% earthquake recall, and 98.15% explosion recall, with only 46 false negatives and 16 false positives. Cross-domain tests yield 84.83% accuracy on hard-rock quarry blasts and 84.72% accuracy on military surface explosions in unconsolidated sediments, verifying strong out-of-distribution generalization capability. Score-CAM visualizations confirm that the model focuses on P/S wave arrivals and the P–S energy gap, shifting systematically with epicentral distance in a manner consistent with seismological wave attenuation theory. These results demonstrate that deep learning can achieve both high classification accuracy and physical interpretability, providing a deployable system for operational seismic monitoring and nuclear test-ban verification.

Abstract The decomposition of earthquake moment tensors into isotropic and deviatoric components is standard in seismology. The deviatoric part is further separated into double‐couple (DC) and non‐double‐couple (NDC) components, with NDC providing insights into source complexity. However, existing methods often yield inconsistent results with different physical interpretation. We propose a novel decomposition method that models an earthquake as two DC subevents, in which the first is determined by P‐wave first‐motion data and the second is derived analytically via moment conservation. This method is simple, efficient, and physically interpretable. We evaluate its stability and apply it to eight global Mw ≥ 7.5 earthquakes (2000–2023) with >40% NDC components. The results align well with previous studies, demonstrating robustness. This method can be extended to multiple subevents when additional constraints, such as aftershock mechanisms, are available. It offers a powerful tool for exploring complex rupture processes and understanding the physical mechanisms of large earthquakes.

The 29 July 2025 Mw 8.8 Kamchatka, Russia, earthquake was the sixth largest instrumentally recorded earthquake. This event was seismically well observed at regional and teleseismic distances, but publicly available near-source data were sparse at the time of the event, presenting unique challenges for rapid source and impact characterization. The U.S. Geological Survey (USGS) National Earthquake Information Center provides global real-time monitoring for earthquakes, including rapid response information products that estimate source characteristics, shaking, and the resulting impacts. We describe the USGS rapid response earthquake information products following the Kamchatka event and discuss their implications for ongoing hazards in the region. We describe potential improvements to our response workflows motivated by this event, including more rapid constraints on source geometries and the automated selection of fault geometries for finite-fault inversions. The rapid response products together support the interpretation of a unilateral southwestward rupture with significant slip on the southwestern end of the rupture extent. The Mw 8.8–9.0 event in 1952, which ruptured a comparable extent of the Kuril–Kamchatka subduction interface, has many similarities to the 2025 rupture. This illustrates that slip deficits may remain following great earthquakes and highlights the usefulness of comparative studies between historic and modern events.

On 8 February 2025, an Mw 7.6 strike-slip earthquake ruptured the Swan Islands Transform Fault in the northern Caribbean near its junction with the Mid-Cayman Spreading Center, providing an important offshore case for investigating rupture dynamics along oceanic transform faults. In this study, we jointly apply teleseismic high-frequency back-projection and low-frequency finite-fault full-waveform inversion to image the multi-scale spatiotemporal evolution of the rupture process. Back-projection results reveal a two-stage rupture characterized by an initial sub-shear propagation lasting approximately 20 s, followed by rapid acceleration to supershear velocities of similar to 5-6 km/s and westward propagation over similar to 80-100 km. Finite-fault inversion shows that coseismic slip is primarily concentrated within similar to 20 km west of the epicenter, with a peak slip of similar to 5.6 m and an overall rupture duration of similar to 40 s. Comparison between high-frequency radiation and low-frequency slip indicates that the most seismic moment was released during the early slow rupture stage, whereas the later fast-propagating segment produced enhanced high-frequency energy but relatively small slip. These observations reveal a pronounced along-strike complementary relationship between slip amplitude and rupture speed, suggesting a transition in rupture dynamics controlled by variations in fault strength, fracture energy, and/or geometric complexity. By combining high-frequency back-projection with low-frequency finite-fault inversion, we obtain a more complete view of the rupture process of offshore earthquakes, which helps clarify rupture propagation characteristics, including supershear behavior, along oceanic transform faults.

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.

The 29 July 2025 Mw 8.8 Kamchatka megathrust earthquake was the largest global earthquake since the 2011 Mw 9.0 Tohoku earthquake and provides an important opportunity to investigate the rupture process of giant subduction events. Here, we combine low-frequency W-phase inversions with high-frequency image deconvolution back-projection (IDBP) to resolve jointly the spatial distributions of coseismic slip and radiated seismic energy. Point-source and finite-fault W-phase inversions show that low-frequency slip is concentrated in the shallow, trenchward portion of the megathrust. In contrast, multi-array IDBP imaging indicates that high-frequency radiation is primarily emitted from the deeper, downdip part of the seismogenic zone.This pronounced high-frequency–low-frequency partitioning closely resembles that observed in other giant megathrust earthquakes, particularly the 2011 Mw 9.0 Tohoku earthquake. The depth-dependent frequency segregation likely reflects mechanical heterogeneity along the plate interface, controlled by along-dip variations in interplate coupling, effective normal stress, and frictional properties. To quantitatively characterize this separation, we combine W-phase waveform modeling with IDBP constraints and calculate the Frequency Dependence Index (FD Index). For the Kamchatka earthquake, the FD Index is 55%, and the centroids of the high- and low-frequency source regions are separated by approximately 70 km. These results provide quantitative constraints on the along-dip mechanical structure of the megathrust and offer new insight into the generation of strong ground motion and tsunami hazards during giant subduction earthquakes.

In this study, we report on a nodal seismic deployment targeting the forebay area of the Three Gorges Reservoir. This deployment aimed to enhance the detection of microearthquakes and refine the imaging of subsurface geological structures. The network's first phase of operation spanned from 2 September 2020 to 16 November 2020. It consisted of 78 short-period seismometers with an approximate interstation distance of 5 km. Using advanced deep-learning algorithms for phase detection and event location, we identified 1165 seismic events in this period, which exceeds the 623 events identified in the manual catalog using the same dataset. The catalog's magnitude of completeness is ML similar to-0:3. The experiment from this deployment can offer guidelines for future microseismic monitoring networks, allowing for the strategic design of nodal seismometer spacing and other key parameters to meet specific observational requirements.

>INTRODUCTION On January 7,2025,at 9:05 AM BJT,a M S 6.8 earthquake（CENC epicenter:28.50°N,87.45°E） struck Dingri County,Xizang Province（hereinafter referred to as the Dingri mainshock）.The inferred moment magnitude,based on regional/teleseismic waveform inversion and back-projection,is approximately M W 7.1.

On January 7, 2025, an Ms6.8 earthquake struck Dingri County, Xigazê City, in the Xizang Autonomous Region. The epicenter, located near the Shenzha-Dingjie fault zone at the boundary between the Qinghai-Xizang Plateau and the Indian Plate, marked the largest earthquake in the region in recent years. The Shenzha-Dingjie fault zone, situated at the boundary between the Qinghai-Xizang Plateau and the Indian Plate, is a key tectonic feature in the India-Eurasia collision process, exhibiting both thrust and strike-slip faulting. This study analyzed the disaster characteristics induced by the earthquake using Differential Synthetic Aperture Radar Interferometry(DIn SAR) to process Sentinel-1 satellite data and derive pre-and post-earthquake surface deformation information. Additionally, high-resolution optical remote sensing data, UAV(unmanned aerial vehicle) imagery, and airborne Li DAR(light detection and ranging) data were employed to analyze the spatial distribution of the surface rupture zone, with field investigations validating the findings. Key results include:(1) Field verification confirmed that potential landslide hazard points identified via optical image interpretation did not exhibit secondary landslide activity;(2) D-In SAR revealed the co-seismic surface deformation pattern, providing detailed deformation information for the Dingri region;(3) Integration of Li DAR and optical imagery further refined and validated surface rupture characteristics identified by optical-In SAR, indicating a predominantly north-south rupture zone. Additionally, surface fracture features extending in a near east-west direction were observed on the southeast side of the epicenter, accompanied by some infrastructure damage;(4) Surface fracture was most severe in high-intensity seismic areas near the epicenter, with the maximum surface displacement approximately 28 km from the epicenter. The earthquake-induced surface deformation zone spanned approximately 6 km by 46 km, with deformation concentrated primarily on the western side of the Dingmucuo Fault, where maximum subsidence of 0.65 m was detected. On the eastern side, uplift was dominant, reaching a maximum of 0.75 m. This earthquake poses significant threats to local communities and infrastructure, underscoring the urgent need for continued monitoring in affected areas. The findings highlight the effectiveness of multi-source data fusion(space-air-ground based observation) in seismic disaster assessment, offering a methodological framework for rapid post-earthquake disaster response. providing a valuable scientific foundation for mitigating secondary disasters in the region.

A devastating Mw 7.7 earthquake struck near Mandalay, Myanmar, on March 28, 2025, causing extensive damage and casualties across Myanmar and neighboring regions. The 2025 event occurred in a well-recognized seismic gap along the Sagaing Fault. Here we focus on the mainshock rupture properties based on back-projection of teleseismic P waves and early aftershock locations, analysis of near-field seismic recordings for the mainshock initiation, and remotely triggered seismicity following the Mw7.7 mainshock. We find that the ∼500 ​km mainshock rupture can be revealed by both rapid back-projection of teleseismic P waves from multiple broadband arrays and early aftershock locations within about 3 ​h from the Thai Meteorological Department (TMD) catalog. The rupture speed went supershear in the southward propagation after the initial bilateral subshear ruptures, as expected for large strike-slip earthquakes of such sizes. Clear fault zone head waves that are reflected along a bimaterial fault interface are observed at the only near-fault station GE.NPW on the slower side about 2.6 ​km away from the Sagaing fault, consistent with the preferred direction of a supershear rupture propagating to the south. In addition, aftershocks from the regional TMD catalog appear to be located mostly to the east of the mainshock rupture. While we cannot completely rule out mis-locations from the one-sided station distribution, these off-fault seismicity could also be explained by reactivations of subsidiary faults within the Shan Plateau, or an eastward dipping of the mainshock rupture plane. Although no immediate foreshocks were found from several nearby stations, we identify one sub-event with magnitude ∼6 ​at the beginning of the mainshock with a slightly different focal mechanism about 20–30 ​km south of the hypocenter determined by the United States Geological Survey (USGS). The mainshock also occurred when the tidal stresses reached its maximum on the right-lateral strike-slip fault, likely indicating that the timing of the mainshock is modulated by the solid earth tides. We find a significant increase of seismic activity near the Thailand/Myanmar border, in multiple (geothermally active) regions of Yunnan province in Southwest China, as well as the Xingfengjian reservoir in the Guangdong province in South China. Because static stress changes from the mainshock are small but negative near the Thailand/Myanmar border, the occurrence of microseismicity in this and other regions can be mainly explained by remote triggering from dynamic stress changes of the mainshock rupture. Our analyses demonstrate the importance of rapid analysis on openly available seismic data and catalog to better understand the rupture properties and triggered seismicity following large earthquakes.

The 8 September 2017 Mw 8.2 Tehuantepec, Mexico earthquake was the second largest normal‐faulting earthquake to occur in a shallow subduction environment since 1976 (GCMT catalog), and the earthquake sequence featured an extremely long‐lasting and productive aftershock activity that deviated from typical intraslab earthquakes. Here we relocated the early aftershocks within 5 days following the mainshock and investigated the source process of the mainshock using back‐projection and finite fault inversion methods. Our results showed that the earthquake rupture propagated along a ∼150‐km‐long, NW‐striking normal fault. After rupturing approximately 100 km, it triggered activity on a ∼40‐km‐long fault located ∼50 km to the northeast. We employed a stochastic branching model to isolate the background seismicity rate, and compared this rate to those of five other earthquakes of similar magnitudes. The results indicated that the background seismicity of the Mexico event occurred at a much higher rate than those of the other five representative earthquakes. Considering that the rupture planes showed similar dip angles and strikes to those of the outer‐rise normal faults, we suggest that the ruptures of the Mw 8.2 earthquake are possibly the reactivation of hydrated outer‐rise normal faults in the subducting slab.

We present a novel finite fault inversion algorithm that combines W-phase finite fault inversion with Image Deconvolution Back-Projection (IDBP) for the determination of coseismic slip models following large earthquakes. This integrated algorithm leverages the strengths of both methods, enabling rapid determination of moment tensor, slip distribution, and centroid location. The application of this integrated algorithm to the analysis of the 2015/04/25 Mw 7.8 Nepal and the 2013/01/05 Mw 7.5 Craig Alaska earthquakes yielded results closely aligned with detailed post-earthquake studies, highlighting the algorithm's accuracy and reliability. By overcoming inherent limitations of individual methods, it provides a comprehensive understanding of the earthquake source process. The algorithm's potential for automated implementation, requiring few parameters, enhances its suitability for near real-time earthquake analysis.

Several physical mechanisms of earthquake nucleation, such as pre-slip, cascade triggering, aseismic slip, and fluid-driven models, have been proposed. However, it is still not clear which model plays the most important role in driving foreshocks and mainshock nucleation for given cases. In this study, we focus on the relationship between an intensive earthquake swarm that started beneath the Noto Peninsula in Central Japan since November 2020 and the nucleation of the 2024 M7.6 Noto Hanto earthquake. We relocate earthquakes listed in the standard Japan Meteorological Agency (JMA) catalog since 2018 with the double-different relocation method. Relocated seismicity revealed that the 2024 M7.6 mainshock likely ruptured a thrust fault above a parallel fault where the M6.5 Suzu earthquake occurred in May 2023. We find possible along-strike and along-dip expansion of seismicity in the first few months at the beginning of the swarm sequence, while no obvious migration pattern in the last few days before the M7.6 mainshock was observed. Several smaller events occurred in between the M5.5 and M4.6 foreshocks that occurred about 4 and 2 minutes before the M7.6 mainshock. The Coulomb stress changes from the M5.5 foreshock were negative at the hypocenter of the M7.6 mainshock, which is inconsistent with a simple cascade triggering model. Moreover, an M5.9 foreshock was identified in the JMA catalog 14 s before the mainshock. Results from back-projection of high-frequency teleseismic P waves show a prolonged initial rupture process near the mainshock hypocenter lasting for ∼25 seconds, before propagating bi-laterally outward. Our results suggest a complex evolution process linking the earthquake swarm to nucleation of the M7.6 mainshock at a region of complex structures associated with the bend of a mapped large-scale reverse fault. A combination of fluid migration, aseismic slip and elastic stress triggering likely work in concert to drive both the prolonged earthquake swarm and the nucleation of the M7.6 mainshock.

On 6 February 2023, an M w 7.8 earthquake occurred along the East Anatolian fault zone (EAFZ) in southeastern T & uuml;rkiye, representing the strongest earthquake in the region in nearly 80 yr. We investigate rupture characteristics and aftershock patterns of the earthquake through focal mechanism calculation, backprojection analysis, and finite-fault inversion. The results show bilateral rupture propagation of the mainshock with transient supershear speed in the southwest portion of the EAFZ, as well as shallower coseismic slip and abundant normal-faulting aftershocks in the same portion. We attribute these earthquake behaviors to the along-strike variation of fault structure of the EAFZ, which features a more complex fault geometry accompanied by numerous short normal faults in the southwest portion. These results shed light on fault segmentation, rupture speed variation, and slip partitioning along the EAFZ, advancing our understanding of fault structural control on earthquake behaviors in a complex multisegment fault system.

In this study, we swiftly determined the focal parameters (focal mechanism, seismic imaging process, magnitude) of the Jishishan earthquake, leveraging a solved fault model to assess the intensity field and casualties promptly. The investigation began by retrieving the source mechanism through the P-wave initial motion and W-phase method. This enabled us to chart the spatial and temporal distribution of energy release in the source area via the back-projection technique. Following this, we estimated the earthquake's intensity field by merging the source inversion findings with the ground motion prediction equation. This analysis facilitated the evaluation of earthquake casualties, utilizing the theoretical intensity field and a casualty assessment model. Our findings indicate that the fault type is a thrust fault, characterized by a unilateral rupture in the direction of NW, with a rupture length spanning approximately 10-15 km and a duration ranging between 8 and 10 s. The earthquake's magnitude varied from M 5.9 to M6.2. The demarcated high-intensity areas, as per our intensity assessment, align closely with the actual survey results. Furthermore, the predicted total casualties and identified critical rescue zones closely match the real-world casualty figures. These insights offer crucial technical support for governmental emergency command and rescue operations.

INTRODUCTION At 01:17 UTC（04:17 on local time） on Feb. 6, 2023, a devastating earthquake with a moment magnitude（M w ） 7.8 occurred in the Gaziantep, southern Turkey. The earthquake was located at 37.174°N and 37.032°E, with a hypocentral depth of