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Subaqueous mass transport deposits (MTDs) attributed to the Mw 6.1 1935 CE Témiscaming earthquake were mapped at 17 sub-bottom acoustic profile survey areas on 11 lakes near Témiscaming, Quebec. Distributed over about 1270 km2, MTDs are the product of shallow failures, up to several metres thick, that occurred along planar surfaces and involved primarily lacustrine sediments. Core samples of unfailed deposits indicate that the failure planes occurred within soft sediments at the top of a glaciolacustrine unit or at the base of overlying lacustrine deposits. Radioisotope dating of sediment samples from six coring sites on Tee and Kipawa lakes confirm that the MTDs are the product of failures triggered by the 1935 CE earthquake. To assess the application of such a mapping study to a paleoseismic investigation, the minimum magnitude of an earthquake that can generate an MTD distribution of 1270 km2 was extrapolated from a published empirical plot. The resulting magnitude of Mw/Ms 5.7–5.8 is less than the instrumental Mw 6.1 magnitude and deemed a reasonable estimation of minimum earthquake magnitude. The distribution of MTDs triggered by the 1935 CE earthquake forms the only such signature within the Témiscaming study area since roughly 8 ka cal B.P. The lack of an analogous, older signature(s) is consistent with the absence of equivalent shaking to the 1935 CE earthquake over this period, but the actual timespan may be shorter and begin when gyttja deposits on slopes became thick enough to be prone to failure from such an event. [ABSTRACT FROM AUTHOR]

Coastal areas around the South China Sea are threatened by potential tsunamis triggered by large earthquakes in the Manila Trench. To quantitively assess the inundation probability caused by tsunamis is crucial for coastal disaster prevention and mitigation. This study focuses on the eastern coast of Hainan Island, which is located to the west of the Manila Trench and may directly face tsunami impact. More than one million tsunami scenarios are simulated considering the randomness of earthquake magnitude, epicenter location, and focal depth. The simulation of numerous tsunami scenarios is based on the unit source superposition method in deep water, which provides boundary conditions for the local model with high spatial resolution for nearshore wave propagation and inundation. Representative waves with different heights and periods are adopted as incident waves in the local model. By involving the joint probability density of incident wave height and period, the spatial distribution of inundation probability is given along the eastern coast of Hainan Island. This study provided an assessment method for the inundation probability, which can more comprehensively consider the uncertainty of earthquakes and provide a more reliable assessment result than that based on refined simulation of several typical scenarios. [ABSTRACT FROM AUTHOR]

Sichuan Province, as one of the active seismic regions in China, has historically suffered from strong earthquakes. The Xingwen Ms5.7 earthquake in 2018 and the Changning Ms6.0 earthquake in 2019, two moderate-magnitude earthquakes that occurred in Sichuan Province in recent years, happened in quick succession and triggered numerous landslides under similar geological structural conditions. These events provide a rare case study for researching the distribution characteristics and cumulative effects of landslides triggered by multiple earthquakes. This study aims to explore the distribution characteristics and superposition effects of landslides from these two earthquakes and to reveal the complexity and regularity of landslides triggered by multiple moderate magnitude earthquakes by comparing and analyzing the spatial distribution, scale size, and influence factors of landslides from the two earthquakes. The results show that 455 landslides were triggered by the Xingwen earthquake event and 511 landslides were triggered by the Changning earthquake event. The landslides are all mainly small and medium-sized, covering a total area of about 2.33 km2, with similar area frequency distribution trends. There is a certain correlation between the number and area of landslides and each factor. In addition, the landslides are mainly distributed in the middle and lower slopes of slower slopes, and the landslide H/L values are positively correlated with the slope gradient. This study reveals the spatial distribution characteristics and morphological parameter features of landslides triggered by the two earthquakes and their aftershocks, which provides a reference basis for landslide hazard assessment and risk management, as well as a case study and inspiration for the study of landslides under the action of multiple earthquakes. [ABSTRACT FROM AUTHOR]

In the northern Andes, partitioning of oblique subduction of the Nazca plate beneath the South American continent induces a northeastward motion of the North Andean Sliver. The strain resulting from this motion is absorbed by crustal faults, which have produced magnitude 7+ earthquakes historically in the Andean Cordillera of Ecuador and southern Colombia. In order to quantify the strain in that area, we derive a high-resolution surface velocity map using InSAR time-series processing. We analyzed 6–8 yr of Sentinel-1 data and combined different satellite line-of-sight directions to produce a reliable velocity map in the east direction. We use interpolated GNSS data to express the velocity map with respect to Stable South America and remove the long-wavelength pattern due to the postseismic deformation following the 2016 Mw 7.8 Pedernales earthquake. The InSAR velocity map finds high east–west shortening strain rates along north–south trending structures within the Western Cordillera and the Interandean valley, with little deformation taking place east of them. This result strengthens the previous proposition of a ∼350 km long Quito-Latacunga tectonic block, forming a restraining bend in the overall right-lateral strike-slip fault system accommodating the northeastward escape motion of the North Andean Sliver. However, the high spatial resolution provided by InSAR indicates that previously proposed boundaries for this block need to be revised. In particular, InSAR results highlight high strain rates (>300 nstrain yr−1) along undescribed active structures, south and west of the proposed limits for the Quito-Latacunga block, respectively, in Peltetec and Ibarra regions. Interestingly, the two areas with the largest strain rates spatially correlate with the proposed areas of large historical earthquakes. Modeling of the InSAR and GNSS velocities in these areas suggests shallow coupling and high slip rates on structures which, previously, were not identified as active. We also demonstrate a slow-down of the shallow aseismic slip on the Quito fault after the Pedernales earthquake, suggesting that stress changes following large megathrust events might trigger transient slip behaviors on crustal faults. The high-resolution strain map provided by this work provides a new basis for future tectonic models in the Ecuadorian and southern Colombian Andes, and will contribute to the seismic hazard assessment in this highly populated area of the Andes. [ABSTRACT FROM AUTHOR]

We estimated the source parameters for local earthquakes near the Idukki reservoir, Kerala. The region falls under seismic zone III, indicating moderate seismicity, and is reported to have witnessed several small to moderate size magnitude earthquakes. Eight local earthquakes with magnitudes ranging between 2 and 3.6 were used during the data analysis of this study. Four key parameters were primarily estimated from the earthquake signals, providing an overall idea about the source characteristics, i.e., seismic moment, stress drop, corner frequency, and source radius. Our estimated moment magnitudes (Mw) range between 2 and 3.4, which are consistent with the reported local magnitude (ML) scale, indicating a minor difference between MW and ML scale. The estimated variations in seismic moment align well with the global model of micro-earthquakes, ranging between 1.2E + 15 and 1.1E + 17 dyn-cm. The source radius mostly varies between 110 and 220 m, with seismic moment exhibiting a linear increase as source size grows. This suggests a clear dependence of seismic moment on the radius of the source. It is likely that the brittle shear-failure mechanism on the fault segment and/or the presence of weak zones would contribute to local earthquakes with smaller source radius. Stress drops for most of the events are relatively low in the study region, ranging from 0.3 to 4.5 bars. The initiation of rupture is evident along an existing fault plane, potentially acting as a contributing factor to the observed lower stress drop values. The stress drop variable with a positive correlation to the seismic moment of the event might indicate a wide range of strength of the crustal rock in the region. Interestingly, both the corner frequency (fc) and maximum frequency (fmax) decrease as seismic moment increases, indicating that both are related to the source process and possibly influenced by the site effects. Finally, we can suggest that the derived source parameters can be utilized to simulate ground motion parameters of historical events, thereby enhancing seismic hazard assessment and facilitating earthquake engineering analyses in future research initiatives. [ABSTRACT FROM AUTHOR]

To enhance the seismicity analysis within a given seismic region, it is crucial to establish a unified earthquake catalog with minimized uncertainties. The preparation of such a unified catalog needs scaling relationships to convert different magnitude types to a homogeneous magnitude. Among the plethora of magnitude types, the moment magnitude (Mw) stands out as a widely utilized metric in modern earthquake risk and recurrence analysis. Hence, the key objective of this study is to expand the Mw earthquake dataset specifically for the Northern Algeria region and its surrounding areas, providing a valuable resource for researchers investigating seismicity in this region and for earthquake magnitudes homogenization. To achieve this objective, surface wave (Ms) and body wave (mb) magnitudes obtained from international agencies were standardized to Mw using newly developed regional empirical relationships based on the general orthogonal regression method (GOR). The use of GOR for magnitude conversions has gained popularity in recent years. However, a critical aspect when employing the GOR method is estimating the standard deviations associated with different magnitude types and subsequently determining the error variance ratio. To address this, the present study leverages recent research works to approximate the standard deviations associated with various magnitudes. By calculating the error variance ratio, derived from the estimation of magnitude uncertainties, the general orthogonal regression method was effectively applied to achieve the desired earthquake magnitude homogenization. Notably, this study fills a significant gap in research conducted in Algeria by developing regional empirical relationships using GOR with appropriate values of the error variance ratio. The expanded Mw dataset serves as a dependable resource used for other earthquake magnitudes homogenization, hence the preparation of a more extensive and unified Mw earthquake catalog for Northern Algeria and its neighboring areas. [ABSTRACT FROM AUTHOR]

This research aims to comprehensively estimate seismicity parameters and create seismotectonic and isoseismal maps for the state of Meghalaya, located in the North-East (NE) region of India using an earthquake catalog collected between 1861 and 2022. The seismic influence zone considered for the study is a circular area with a radius of 350 km around Shillong city (latitude 25.57° N and longitude 91.88° E). Distinct magnitude classes, such as 3.50–3.99, 4.00–4.99, 5.00–5.99, 6.00–6.99, and ≥ 7.00, are considered for analysis, and corresponding completeness periods are obtained as 40, 60, 100, 160, and 130 years, respectively. The study area seismicity parameters a and b values of the Gutenberg–Richter (G–R) relationship are obtained with values ranging from 5.50 to 6.23 and 0.70 to 0.75, respectively. This study further estimates earthquake magnitude occurrence probabilities for 1, 50, and 100 years, as well as the associated return periods. Additionally, seismotectonic maps are developed to provide crucial insights into seismic hazards within the study area. These maps delineate fault lines, active tectonic structures, and seismic zones, facilitating the assessment of potential seismic risks. Intensity-based isoseismal maps are generated to assess the influence of the past five major earthquake occurrences within the study area. It is observed that, if a recurrence of past seismic events occurs at or near the same region, a maximum intensity XI on the Medvedev–Sponheuer–Karnik (MSK) intensity scale might be felt in the study area. The outcome of this study will serve as a valuable resource for seismic hazard assessment specific to the Meghalaya region. [ABSTRACT FROM AUTHOR]

Earthquakes begin with abrupt shifts along the faults. These movements release seismic waves that propagate through the Earth, shaking the ground as a result of the stored "elastic strain" energy being released. Property loss and human deaths occur due to improper design of structures under the earthquake loading conditions. It is observed that Peninsular India witnessed steady-to-serious earthquakes in the last 50 years. Amaravati is the prospective capital city of Andhra Pradesh State, which is situated on the Coromandel Coast of Peninsular India. The upcoming capital city, Amaravati, requires an earthquake hazard analysis because important engineering structures and infrastructure systems will be constructed in the near future. In this study, a probabilistic approach is used to assess the earthquake hazard for Amaravati City (latitudes: 16∘24 ′ 36 ′ ′ –16∘35 ′ 24 ′ ′ N and longitudes: 80∘24 ′ 25 ′ ′ –80∘36 ′ 18 ′ ′ E), India. The seismic risks of Amaravati City presented in terms of the configuration of ground motion parameters, peak ground acceleration (PGA), and spectral response acceleration ( S a ) at 0.05 s and 1 s for 2% and 10% Risks of Exceedance in 50 years, are produced. The uncertainties involved in seismic risk prediction are accounted for by selecting different attenuation relations developed for globally shallow crustal intraplate earthquakes with a logic tree approach. Additionally, the seismic risk values are disaggregated for Amaravati City (16∘31 ′ 37 ′ ′ N and 80∘29 ′ 46 ′ ′ E) to understand the individual contributions of seismic sources in terms of earthquake magnitude and site distance. The uniform hazard spectra are developed for the important places of the Amaravati Capital City and are compared with the Indian seismic code [IS 1893 (Part 1): Criteria for earthquake-resistant design of structures — Part 1: General provisions and buildings] for the rocky site. It is found that the estimated PGA values for Amaravati City are higher than the values recommended by IS 1893 (Part 1) for the rocky site. The results of this study will be very helpful for the composition of earthquake-resistant infrastructures in Amaravati City. [ABSTRACT FROM AUTHOR]

School counsellors who work with children and young people within the education system and have experienced trauma themselves can be significantly affected by challenging events. The current research focussed on understanding the post-trauma needs of school counsellors who continue their work in earthquake-affected regions. A phenomenological design was used in this study. Twenty-two school counsellors who experienced the 7.7 and 7.6 magnitude Maraş earthquakes in Türkiye in 2023 and are still working in the affected areas were interviewed. The findings showed that the needs of school counsellors after the earthquake could be categorized into three themes: (1) I want practice, not theory, (2) I want hope for myself and (3) I want people for my profession. Specifically, school counsellors reported a need for trauma and crisis intervention training, individual support, supervision and physical resources (e.g. collaboration, accommodation and stationery). The implications for school counselling are discussed. [ABSTRACT FROM AUTHOR]

The slow motion of tectonic plates over thousands of kilometers is intermittently interrupted by great earthquakes with sudden slips localized near convergent plate boundaries. We developed a subduction model that self‐consistently integrates buoyancy forces, diffusion and dislocation creep, and inter‐plate friction. From the nonlinear dynamics emerge long‐term plate motions that achieve velocities of ≈5 ${\approx} 5$ cm/year, effective viscosities of ≈1019 ${\approx} 1{0}^{19}$ Pa⋅ $\cdot $s below plates, and sudden slips up to ≈10 ${\approx} 10$ m repeating every several hundred years. Along‐strike resistance arising from long‐wavelength variation of coseismic slip is naturally incorporated with a rupture length scale, L∼ $\tilde{L}$. Computations with L∼∼103 $\tilde{L}\sim 1{0}^{3}$ km generate events with Mw≈9 ${M}_{w}\approx 9$. When L∼ $\tilde{L}$ decreases, there is a commensurate decrease in the effective moment of rupture events. Predicted long‐term plate velocities, mantle viscosities, cycles of stress loading and release, and rupture event size and magnitude all show good agreement with observations. Plain Language Summary: Subduction zones are regions where one tectonic plate slides under another at a velocity of several centimeters per year, but the plates can slip suddenly during great earthquakes in the convergent plate boundary. We developed a model that self‐consistently integrates tectonic forces and material properties. This model replicates steady plate motions of several centimeters per year and rupture events with slips up to 10 m and a period of several hundred years. Mantle viscosities and space–time patterns of stress accumulation and release also align with observations. During great earthquakes, the rupturing segment advances rapidly but is held by neighboring non‐rupturing segments. Resisting forces arising from this along‐strike variation are naturally incorporated and tested with different rupture length scales, and Magnitude 7–9 earthquakes emerge. The models highlight the significance of along‐strike slip variations in modulating earthquake processes. Key Points: Development of a self‐consistent subduction model that integrates the dynamics of plate tectonics and great megathrust earthquakesWith realistic model parameters, predicted long‐term plate motions and seismic cycle behaviors align with observations in subduction zonesThe along‐strike resistance arising from slip variations plays a critical role in influencing the magnitude of a rupture event [ABSTRACT FROM AUTHOR]

To improve the performance of earthquake early warning (EEW) systems, we propose an approach that utilizes the time-dependence of P-wave displacements to estimate the earthquake magnitude (M) based on the relationship between M and the displacement. The traditional seismological understanding posits that this relationship achieves statistical significance when the displacement reaches its final peak value, resulting in the adoption of time-constant coefficients. However, considering the potential for earlier establishment of the relationship's significance than conventionally assumed, we analyze waveforms observed in Japan and determine the intercept in the relationship as a function of time from the P-wave onset. We demonstrate that our approach reduces the underestimation of M in the initial P-wave stages compared to the conventional technique. Consequently, we find a significant rise in the number of earlier warnings in the Japanese railway EEW system. Due to the inherent trade-off between the immediacy and accuracy of alarm outputs, the proposed method unavoidably leads to an increase in the frequency of alerts. Nonetheless, if deemed acceptable by system users, our approach can contribute to EEW performance improvement. [ABSTRACT FROM AUTHOR]

The Eastern Tianshan region, influenced by the far-field effect of northward compression and expansion of the Qinghai-Xizang block, features highly developed Late Quaternary active faults that exhibit significant neotectonic activity. Historically, the Barkol-Yiwu Basin, located to the north of the Eastern Tianshan, experienced two major earthquakes in 1842 and 1914, each with a magnitude of M71/2. In contrast, the Hami Basin on the southern margin of the Eastern Tianshan has no historical records of any major earthquakes, and its seismic potential, mechanisms, and future earthquake hazards remain unclear. Based on satellite image interpretation and field surveys, this study identified a relatively recent and well-preserved seismic surface rupture zone with good continuity in the Liushugou area of the western segment of the Northern Margin Fault of the Hami Basin (HMNF), which is the seismogenic structure responsible for the rupture. The surface rupture zone originates at Kekejin in the east, extends intermittently westward through Daipuseke Bulake and Liushugou, and terminates at Wuzun Bulake, with a total length of approximately 21 km. The rupture zone traverses the youngest geomorphic surface units, such as river beds or floodplains and first-order terraces (platforms), and is characterized by a series of single or multiple reverse fault scarps. The morphology of fault scarps is clear, presenting a light soil color with heights ranging from 0.15 m to 2.13 m and an average displacement of 0.56 m, suggesting that this surface rupture zone likely represents the most recent seismic event. Comparison with historical earthquake records in the Eastern Tianshan region suggests that the rupture zone may have been formed simultaneously with the Xiongkuer rupture zone by the 1842 M71/2 earthquake along the boundary faults on both sides of the Barkol Mountains, exhibiting a flower-like structural pattern. Alternatively, it might represent a separate, unrecorded seismic event occurring shortly after the 1842 earthquake. The estimated magnitude of the associated earthquake is about 6.6~6.9. Given that surface-rupturing earthquakes have already occurred in the western segment, the study indicates that the Erdaogou–Nanshankou section of the HMNF has surpassed the average recurrence interval for major earthquakes, indicating a potential future earthquake hazard. [ABSTRACT FROM AUTHOR]

The ongoing Indo-Eurasian convergence leads to great megathrust earthquakes in the Himalayan region, affecting the life and infrastructure of the world's most densely populated areas adjoining the Himalaya. The ~2500-km long Himalayan arc has experienced several earthquakes having magnitude greater than Mw 7.5 during the last millennium. While palaeoseismic and fault slip-rate studies have gained pace during the last few decades in the Western and Central Himalayan regions, the Eastern Himalaya and contiguous regions remain understudied. Even though geological evidence of great earthquakes in 1697, 1714, and 1950 CE has been reported in the Eastern Himalaya, the lateral extent of their rupture is still debated due to limited and sparse palaeoseismic studies. Furthermore, the segmentation of the eastern Himalaya raises concerns about the role of sub-surface transverse structures in controlling the rupture propagation of large to great earthquakes. Hence, we have compiled all the palaeo-earthquake studies carried out in the eastern part of the Himalayan convergent plate margin of the Indian Subcontinent and identified the potential gap areas with the slip deficit, which are capable of generating Mw > 8 earthquakes in the future. This study aims to provide a foundation for future palaeo-earthquake studies, which are crucial in understanding the earthquake recurrence and the strain release pattern in the region. [ABSTRACT FROM AUTHOR]

This work aims to develop and share a high-quality seismic dataset for the East Anatolian Fault Zone (EAFZ), which is a highly active seismic area that is prone to earthquakes, as evidenced by the two major earthquakes of magnitude 7.8 and 7.6 that occurred on February 6, 2023 in central Türkiye and northern and western Syria. The dataset described here (available at https://doi.org/10.5281/zenodo.13838992 , Colavitti et al., 2024) encompasses seismic events from January 1, 2019, to February 29, 2024, focusing on small-to-moderate earthquakes from ML between 2.0 and 5.5 and is intended as a useful tool for researchers working on seismic source characterization and strong motion parameters. The dataset consists of 9,442 events recorded by 271 stations and includes a total of 270,704 seismic phases (148,223 P and 122,481 S). The Complete Automatic Seismic Processor (CASP) software package ensures accurate arrival times and refined earthquake locations, while the local magnitude is calibrated using a non-parametric approach. In addition to the earthquake catalog, the dataset features strong motion parameters such as selected Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), as well as Fourier Amplitude Spectra (FAS) in the frequency range from 0.05 to 47.2 Hz. The disseminated product aims to support applications in spectral decomposition using the Generalized Inversion Technique (GIT), promote investigations in Local Earthquake Tomography (LET) and contribute to the development of Ground Motion Prediction Equations (GMPEs). Long-term objectives include studying the spatio-temporal evolution of seismicity to identify preparatory processes for significant earthquakes, integrating this data with geodetic investigations, and enhancing earthquake hazard assessments. [ABSTRACT FROM AUTHOR]

Background: Faulting induced by earthquakes and its analysis are of great importance for areas with high probability of earthquakes. However, there has been no particularly effective methods to evaluate the damage and applicable solutions for recovery. In this paper, the damage from Türkiye earthquakes is investigated by authors, which has important theoretical significance and practical value. On 6 February, 2023, two successive earthquakes with magnitudes (Mw) of 7.8 (called Pazarcık earthquake) and 7.6 (Ekinözü earthquake) occurred in the south-eastern part of Türkiye. The total length of the surface ruptures was more than 500 km long and resulted in striations reflecting the sinistral faulting and extensive ground deformations. In this study, the authors present the outcomes of the investigations on the surface ruptures, their characteristics, stress field associated with both earthquakes, shear strength property of fault segments and the damaging effects on various structures and made some recommendations with the purpose of how to build structures in active fault zones and decrease the negative effects of faulting on structures. Results: Besides summarizing the main characteristics of the world-shaking Kahramanmaraş earthquake doublet in southeast Türkiye in 2023, this study described the main features of the surface ruptures, their relation to the inferred crustal stresses in Türkiye, and the damaging effects on the major engineering structures. The observations and inferences are of great significance for understanding the causes of earthquakes and future seismic risk assessment. Various laboratory experiments were performed on the samples of fault gouge gathered from the sites of surface ruptures and these experimental results provided very valuable quantitative information on the constitutive models of the fault zones. The observations clearly showed that it is almost impossible to prevent damage on structures due to surface ruptures, if certain engineering principles such as increasing higher ductility, lowering gravitational center and/or the implementations of raft foundations are followed. Conclusions: The stress state inferences obtained from the striation of the fault surface ruptures as well as from the focal plane solutions are expected to be useful to evaluate the regional stress state of the earthquake region. Assessments indicated that the stress states in Arabian plate and Anadolu platelet are different from each other. However, in-situ direct stress measurement techniques would be quite useful to validate the stress state inferred in this study. The laboratory experiments on samples gathered from the fault outcrops of the earthquakes using direct shear tests, stick-slip tests as well as conventional tensile, compressive and triaxial tests provided the quantitative values for the parameters of constitutive laws for fault zones, which can be utilized in the numerical simulation of earthquakes. If a fault break happens to be just passing underneath the structures, it is almost impossible for mankind to prevent the damage to structures. However, the authors made some recommendations to reduce the negative effects of fault ruptures on structures. These recommendations are such that the structures should be built as ductile and redundant structures with lower center of gravity and raft foundations. Dam construction should be on active faults should be avoided. If they are to be built for whatever reason, they should be of rock-fill type. As tubular structures and tunnels would be generally subjected forced displacement field, it is recommended to utilize flexible joints, segmented and enlargement to deal such displacement fields. [ABSTRACT FROM AUTHOR]

The article discusses the Collaboratory for the Study of Earthquake Predictability in China (CSEP) and its experiment design and preliminary results in CSEP2.0. It highlights the development of earthquake forecasting models and retrospective forecasting experiments conducted in high-seismicity regions, particularly in the North-South Seismic Belt in Central China. The study evaluates the effectiveness of forecasting models like the Pattern Informatics (PI) algorithm and the Relative Intensity (RI) algorithm, showing consistency with observed earthquake activity within a 5-year forecast window. The research aims to compare forecasting models on short-term, medium-term, and long-term scales, fostering international collaboration in earthquake prediction research. [Extracted from the article]

The Mediterranean Hellenic Arc subduction zone (HASZ) has generated several MW≥ ${\mathrm{M}}_{W}\ge $8 earthquakes and tsunamis. Seismic‐probabilistic tsunami hazard assessment typically utilizes uniform or stochastic earthquake models, which may not represent dynamic rupture and tsunami generation complexity. We present an ensemble of ten 3D dynamic rupture earthquake scenarios for the HASZ, utilizing a realistic slab geometry. Our simplest models use uniform along‐arc pre‐stresses or a single circular initial stress asperity. We then introduce progressively more complex models varying initial shear stress along‐arc, multiple asperities based on scale‐dependent critical slip weakening distance, and a most complex model blending all aforementioned heterogeneities. Thereby, regional initial conditions are constrained without relying on detailed geodetic locking models. Varying epicentral locations in the simplest, homogeneous model leads to different rupture speeds and moment magnitudes. We observe dynamic fault slip penetrating the shallow slip‐strengthening region and affecting seafloor uplift. Off‐fault plastic deformation can double vertical seafloor uplift. A single‐asperity model generates a MW∼ ${\mathrm{M}}_{W}\sim $8 scenario resembling the 1303 Crete earthquake. Using along‐strike varying initial stresses results in MW∼ ${\mathrm{M}}_{W}\sim $8.0–8.5 dynamic rupture scenarios with diverse slip rates and uplift patterns. The model with the most heterogeneous initial conditions yields a MW∼ ${\mathrm{M}}_{W}\sim $7.5 scenario. Dynamic rupture complexity in prestress and fracture energy tends to lower earthquake magnitude but enhances tsunamigenic displacements. Our results offer insights into the dynamics of potential large Hellenic Arc megathrust earthquakes and may inform future physics‐based joint seismic and tsunami hazard assessments. Plain Language Summary: The Mediterranean region around Greece and Crete is a hotspot for earthquakes and tsunamis. Here, the tectonic plates of Africa and Europe collide. History shows that this region has experienced damaging earthquakes. These earthquakes can cause tsunamis, sea waves that may lead to widespread destruction along coastlines. Our study aims to understand better how future earthquakes can be modeled. We use computer models to simulate different earthquake scenarios. Initially, we use simple conditions in our models, showing that if an earthquake propagated across the entire region, it could reach a moment magnitude of 9. When we move the earthquake's location within our model, the size and impact of the resulting earthquake change; some locations lead to larger seafloor displacements, which may cause more dangerous tsunamis. When introducing more complicated loading and fault strength conditions, the resulting earthquakes become smaller, consistent with historical observations. We also simulate how the fault‐surrounding rocks can deform during an earthquake. Such deformations can increase the uplift of the seafloor, increasing the potential for tsunamis. Our work shows that computer modeling can be a powerful tool for understanding earthquakes and tsunamis and better prepare for future events. Key Points: We present the first 3D dynamic rupture earthquake scenarios for the Hellenic Arc megathrustEpicenter location is a dominant factor controlling the occurrence and intensity of shallow slip and upliftDynamic rupture complexity tends to lower earthquake magnitude but enhances tsunamigenic displacement [ABSTRACT FROM AUTHOR]

The Epidemic-Type Aftershock Sequence (ETAS) model is currently the most powerful statistical seismicity model that reproduces the general characteristics of earthquake clustering in space and time. However, its application can be hampered by biased parameter estimations related to earthquake catalogue deficiencies, particularly in regions where the spatial coverage of local recording networks is relatively poor. Here, we systematically investigate the possible influences of the effect introduced by data truncation through the choice of the cut-off magnitude (⁠|${{m}_{\rm cut}})$| and missing events due to heterogeneity of the seismic network on ETAS parameter estimates along the East African Rift System (EARS). After dividing the region into six source zones based on rheological and mechanical behaviours, the ETAS model is fitted to the earthquakes within each zone using the Davidon–Fletcher–Powell optimization algorithm. The fits and variations in parameter estimates are compared for each zone to the others and the seismological implications are discussed. We found that some parameters vary as a function of |${{m}_{\rm cut}}$| primarily driven by changes in catalogue size. Additionally, a systematic regional dependency of ETAS parameters is found across source zones. Furthermore, a median heat flow value for each analysed source zone in the EARS is calculated. In contrast to previous findings in other tectonic settings, the results reveal no significant correlations between the crustal heat flows and the ETAS parameters describing earthquake productivity (⁠|${{K}_0}$|⁠) and the relative efficiency of an earthquake with magnitude M to produce aftershocks (⁠|$\alpha $|⁠). Our findings have significant implications for understanding the mechanisms of earthquake interaction and, therefore, provide tight constraints on the model's parameters that may serve as a testbed for existing earthquake forecasting models in this region where the vulnerability of local buildings and structures exacerbate seismic risk. [ABSTRACT FROM AUTHOR]

We develop and apply a dynamic economic simulation model to analyze the multi-regional impacts of, and mechanisms of recovery from, a major disaster, the HayWired scenario — a hypothetical Magnitude 7.0 earthquake affecting California's San Francisco Bay Area. The model integrates loss pathways: capital stock damage, labor supply shocks due to short-term population displacement and longer-run out-migration from damaged areas, and the exacerbating effects of damage to transportation infrastructure capital, as well as various aspects of static and dynamic economic resilience. With input substitution-based static inherent resilience and dynamic resilience in the form of optimal intertemporal and spatial investment allocation, gross output losses range from 0.5 percent to 6 percent across regions, and welfare losses are 0.4 percent statewide but can be ten times as large in hardest-hit areas. Large-scale reconstruction investment is supported by substantial interregional transfers of resources through intra-state trade. Increased output via firms engaging in the key adaptive resilience tactic of production recapture can alleviate a substantial fraction of losses—but only if upstream and downstream barriers to recovery can be lowered quickly. [ABSTRACT FROM AUTHOR]

A series of undrained cyclic triaxial tests were carried out on loose sand specimens, including encased and non-encased granular columns, to evaluate the cyclic behavior and liquefaction resistance of the ground improved by granular columns. It was found that using geogrid encasements could effectively reduce cumulative settlements and mitigate the liquefaction potential when its tensile stiffness was high enough. Another finding was the inefficiency of flexible geosynthetic encasements to delay and mitigate the liquefaction in granular columns with the possibility of clogging. Findings indicated that the improvement of a loose ground with encased granular columns not only decreased the liquefaction-induced ground deformation but also significantly reduced the effect of earthquake magnitude on the ground deformation. It was also found that using the granular column and encasing it with a high-stiffness encasement not only slowed down the rate of ground softening during the cyclic loading experience but also decreased the dissipation of energy. [ABSTRACT FROM AUTHOR]

With the highly nonlinear relationship between various seismic feature indicators and earthquakes, the researchers can hardly construct an earthquake model. Meanwhile, the lack of samples for destructive earthquakes also leads to inaccurate medium-to-short-term earthquake magnitude predictions. Therefore, this study proposes a novel model for earthquake prediction, named variant detector bagging algorithm (V-detector-bagging). First, we adopt the geological distribution of earthquakes and faults as a criterion to select the appropriate history catalog data area, and the seismic indicators are calculated through the Gutenberg–Richter laws and Panakkat indicators. Then, we propose the V-detector-bagging algorithm, which combines the V-detector algorithm with the bagging method. The proposed algorithm converts the self-tolerance process into a cycle process, during this process, different selves guide samples to spread widely, generate various detectors covering more wide nonself areas, fill holes that are not covered by detectors in nonself areas, and reduce the false negative rate. Thus, the V-detector-bagging algorithm improves the detection performance of the V-detector. Finally, through experimental validation analysis, the proposed algorithm ranked first in the detection rate on Sichuan and Xinjiang catalog data compared to the popular machine learning methods used in predicting earthquakes and the original V-detector algorithm, with Xinjiang yielding the best results. [ABSTRACT FROM AUTHOR]

In the twenty-first century, the seismic design of buildings seems to have become a fully recognized topic. There are guidelines and standards which should be taken into account by designers in seismic areas. Designers using modern international guidelines have ascertained that the behavior of structures is not as expected. New challenges in the construction industry result in the construction of structures with new, unusual shapes. These are structures that do not meet the assumptions of safe construction in seismic areas. Contemporary buildings are also characterized by their irregular distribution of structural elements. Such solutions are not beneficial from the point of view of seismic engineering and can lead to reduced dynamic resistance and damage in such structures. In this paper, a five-storey, irregular-shaped reinforced concrete (RC) building model was subjected to different earthquakes with varying magnitudes, PGA (peak ground acceleration) and PGV (peak ground velocity) values, and durations of the intense shock phase. Once the model was verified using previous in situ measurements, the building model was subjected to five earthquakes. A numerical nonlinear analysis of the building was performed using a verified FEA (finite element analysis) model in the time domain through non-linear time history analysis with the Broyden–Fletcher–Goldfarb–Shanno (BFGS) method. The building's dynamic properties were measured using various methods of excitation. The model was influenced, among others, by two far-field representative events caused by the last earthquake in Turkey, which resulted in strong ground motion. The analysis results identified the locations of structural damage and allowed for the assessment of the structure's dynamic resistance. The results of the calculations prove that the duration of the intensive phase of extortion is one of the reasons for building damage in earthquake-prone areas. Building damage occurs with earthquakes that are characterized by an intensive phase of excitation with a long duration and high values of velocity in the earthquake components. The article highlights the inadequate dynamic resistance of the building, leading to excessive displacements and unfavorable structural solutions. Damage to buildings at this earthquake intensity caused damage to the load-bearing structure, which was not designed for such intensities. This paper is a research report with a specific case study of medium-rise irregular RC buildings. [ABSTRACT FROM AUTHOR]

The increasing frequency of earthquakes in Kuwait raises concerns regarding soil liquefaction. Currently, there is no soil liquefaction potential map for Kuwait, even for soil profiles along coastal shores, where the groundwater table is near the surface. To address this gap, investigations and assessments were carried out and ArcMap 10.8 was used to establish five soil liquefaction hazard potential maps for Kuwait for different earthquake scenarios based on available borehole logs. The popular methods for evaluating soil liquefaction hazard are the simplified approach proposed in the National Center for Earthquake Engineering Research workshop, which is based on standard penetration tests (for determining the safety factor), and Luna and Frost's (1998) method to assess the liquefaction potential index. Notably, standard penetration test blows were used to investigate the variations in the soil relative density below the surface, describe seismic sources, and estimate peak ground accelerations (calculated using Cornell's equation and verified using ground-motion models). Southern Kuwait was highly vulnerable to soil liquefaction potential (local earthquake moment magnitude of 5.5); this was confirmed by the documented structural damage. Such maps can be used to identify the areas vulnerable to soil liquefaction and limit the risk to infrastructure. [ABSTRACT FROM AUTHOR]

We investigate the relationship between the seismogenic behavior of global megathrusts and various subduction parameters. We performed a parametric approach by implementing three decision tree‐based Machine Learning (ML) algorithms to predict the b‐value of the frequency‐magnitude relationship of seismicity as a non‐linear combination of subduction variables (subducting plate age and roughness, slab dip, convergence speed and azimuth, distance to closest ridge and plate boundary). Using the Shapley Additive exPlanations (SHAP) to interpret the ML results, we observe that plate age and subduction dip are the most influential variables. The results suggest that older, shallow‐dipping plates contribute to low b‐values, indicating higher megathrust stress. This pattern is attributed to the higher rigidity of older plates, increasing flexural strength, and generating a shallow penetration angle, increasing the frictional interplate area and intensifying the megathrust stress. These findings offer new insights into the non‐linear complexity of seismic behavior at global scale. Plain Language Summary: We carried out a study to investigate how certain characteristics of subduction zones, where one tectonic plate slides under another, influence the earthquakes behavior. Using different machine learning algorithms we examined how different variables in these zones affect the relative amount of small versus large earthquakes, parameterized by the slope of a log‐normal relationship between frequency and magnitude of events, known as the b–value. Our analysis showed that the age of the subducting plate and the angle at which it dips under another plate are the most influential factors in earthquake behavior. In particular, we found that older plates with shallow subduction angles are associated with higher stress at the subduction interface, which in turn, increases the probability of large earthquakes, decreasing the b‐value. This is because older, colder plates are more rigid than young and hot plates, which increases their resistance to bending, augmenting the contact area between the plates and the friction between them. These findings shed light on the complex dynamics of seismic activity on a global scale and provide valuable information for understanding the earthquake behavior worldwide. Key Points: The non‐linear relationship between subduction parameters and seismogenic behavior, as represented by the b‐value, is exhibitedPlate age and subduction angle are shown as the most impactful parameters in megathrust stress worldwideOlder subducting plates with lower subduction angles are associated with lower b‐values, implying higher megathrust stress, and viceversa [ABSTRACT FROM AUTHOR]

This research breaks new ground in earthquake prediction for Los Angeles, California, by leveraging advanced machine learning and neural network models. We meticulously constructed a comprehensive feature matrix to maximize predictive accuracy. By synthesizing existing research and integrating novel predictive features, we developed a robust subset capable of estimating the maximum potential earthquake magnitude. Our standout achievement is the creation of a feature set that, when applied with the Random Forest machine learning model, achieves a high accuracy in predicting the maximum earthquake category within the next 30 days. Among sixteen evaluated machine learning algorithms, Random Forest proved to be the most effective. Our findings underscore the transformative potential of machine learning and neural networks in enhancing earthquake prediction accuracy, offering significant advancements in seismic risk management and preparedness for Los Angeles. [ABSTRACT FROM AUTHOR]

Background: The landslide inventory of the western flank of Mount Oku, Cameroon, includes spreads or complex landslides, indicating sudden soil weakening, possibly due to seismic activity or heavy rainfall causing groundwater rise. These landslides were likely triggered between 2009 and 2018 based on the dates of the aerial imagery. Identifying triggers for past landslides remains a major unresolved issue in landslide science. However, understanding these triggers is crucial for accurately assessing future landslide hazards. Methodology: In this paper, we investigate the possibility of earthquakes to precondition landslide development or reactivation during climatic events. By assuming a magnitude 5.2 earthquake, an epicenter of 10 km from this area, and different wetness conditions, the factor of safety (FS) and Newmark displacement (ND) models were calculated for shallow and deep-seated landslides with sliding depths of 3 and 7.5 m. Afterward, the relationship between FS, assumed ND, and observed landslides was analyzed in a cluster analysis, to derive patterns of climatically and seismically triggered landslides. Results: The comparison of FS maps and FS values of the observed landslides revealed that especially for landslides at 7.5 m depth, most sites that are stable during dry conditions become instable under saturated conditions, indicating a climatic trigger. At 3 m depth, however, some landslide sites that are still marginally stable under saturated conditions, display relatively high ND values for the investigated hypothetical earthquake, indicating a possible seismic influence. In the cluster analysis, we clustered the observed landslides according to their distances to rivers and topographic ridges and obtained three clusters. Landslides from cluster 3 with 31% of the landslides display medium to high ND for the assumed earthquake, and were found near ridges and farther away from rivers, suggesting seismic triggering. Cluster 2, with 12% of landslides closer to rivers, suggested climatic origins. Thus, while climate is a critical landslide contributing factor, seismic events may also contribute, either by predisposing to landslides or by reactivating them alongside climatic factors. These results enable the establishment of more precise and effective landslide mitigating measures considering mostly rainfall but also earthquakes as possible triggers. [ABSTRACT FROM AUTHOR]

The Central and South‐Central Andes form a "two‐sided" mountain belt bounded by distinct zones of convergence in the forearc and backarc flanks. Previous geodetic interseismic deformation studies found that the forearc to backarc velocity field is better explained when elastic models allow reverse aseismic slip on the Andes eastern‐flank décollement faults. Here, we extend the earlier interpretation of interseismic motion and argue that normal aseismic creep of the Precordillera décollement is required to explain backarc Global Navigation Satellite System displacements during the co‐ and early postseismic phases of the 2015 Illapel, Chile, earthquake. This model significantly reduces the previously reported overlap between coseismic slip and afterslip on the megathrust of this earthquake, consistent with the expectation that these slip modes are spatially partitioned. These findings have direct implications for estimating recurrence interval and slip rate, and for probabilistic seismic hazard analysis on both sides of the orogen. Plain Language Summary: Between consecutive earthquakes in the Central and South‐Central Andes, during what is known as the interseismic phase, the traditional Nazca‐South America two‐plate model underpredicts the surface Global Navigation Satellite System (GNSS) velocities on the east side of the mountain belt. Previous studies show that adding an "Andean microplate," thus forming a three‐plate model, kinematically explains the observed velocity field on both sides of the Andes. We analyzed the GNSS coseismic displacements caused by the Mw 8.3 2015 Illapel, Chile, earthquake, and found that the traditional two‐plate model also underpredicts GNSS observations in the eastern side of the Andes. We show that adding the Andean microplate to the model, in the same manner as for the interseismic phase, and allowing aseismic slip on the detachment interface beneath it significantly reduces the observed surface displacements misfit. We also show that this holds for the displacements observed 50 days after the main shock, evidencing that the detachment geometry slips before, during, and after a large magnitude earthquake. Using the three‐plate model produces fault slip distributions that decrease overlap between local maxima in coseismic and aseismic slip, consistent with expectations from rate‐ and state‐dependent friction laws. Key Points: Revised co‐ and postseismic slip models account for forearc‐backarc coupling by allowing slip on the Argentine Precordillera décollementObserved continuous and survey Global Navigation Satellite System displacements on both sides of the Andes are better explained by models with a décollementAdding a décollement significantly reduces megathrust coseismic slip and afterslip overlap, compatible with rate and state friction law [ABSTRACT FROM AUTHOR]

On 8 October 2023 (UTC), unique earthquakes occurred in the Izu‐Ogasawara Arc, Japan, in which the P‐ and S‐phases were barely visible and only the T‐phases were evident, followed by tsunamis that reached islands in the Izu‐Ogasawara Arc and a wide area of the Pacific coast of southwest Japan. Our estimated T‐phase source area coincides with the Sofu Seamount, which was previously unrecognized as an active submarine volcano. A bathymetric survey of the seamount conducted 1 month after the event revealed characteristics of the seamount with a caldera and a central cone. Compared to the bathymetry in 1987, the topography in the caldera had changed significantly such as a crater forming in the central cone. This seamount is likely to be an active volcano. The topographic changes on the caldera‐sized scale that occurred at the caldera can be explained as a source of the October tsunami. Plain Language Summary: On 8 October 2023 (UTC), earthquakes were followed by tsunamis in the Izu‐Ogasawara Arc of Japan that were higher than that estimated from the magnitude of the earthquake. The tsunamis were observed on islands in the Izu‐Ogasawara Arc and a wide area of the Pacific coast of southwest Japanese islands. Strong T‐phases that are underwater acoustic waves were observed accompanying that event. We estimated that the T‐phases originated from the area around the Sofu Seamount, which has not been recognized as an active submarine volcano until now. One month after the event, we conducted a bathymetric survey of the seamount and revealed the characteristics of a caldera and a central cone within the caldera. Compared to the bathymetric data obtained in 1987, the caldera and central cone topography have changed significantly, such as a crater forming in the central cone, indicating that this seamount is likely to have been an active submarine volcano. The topographic changes that occurred at the depth of the caldera (∼1,000 m) and its scale (diameter ∼5 km) can be associated with the source of the tsunami on 8 October 2023. Key Points: A bathymetric survey of the Sofu Seamount was conducted after the unique T‐phase dominant earthquakes and tsunamis on 8 October 2023Compared to data in 1987, the caldera and central cone topography have changed, indicating that this seamount is an active submarine volcanoThe observed seafloor displacement at the caldera scale may have contributed to the source of the tsunami on 8 October 2023 [ABSTRACT FROM AUTHOR]

We develop a methodology to compile an objective tremor catalog by utilizing distinctive event features that differentiate tectonic tremors from non‐tremor events, and combining the envelope cross‐correlation method with clustering technique and neural network. This approach enables tremor extraction without subjective criteria, allowing for the detection of previously overlooked short‐duration tremors. The event features employed to distinguish tremors and non‐tremor events are depth, the mean amplitudes at high and low frequencies, the ratio of these two amplitudes, and event duration. The duration is defined as the minimum period that contains 50% of the seismic energy. The application of this method to western Japan detects 1.7 times more tremors than the previous studies, with the durations of 0.3–∼100 s. The events with short durations are considered low‐frequency earthquakes. The relationship between seismic moment and duration of the detected tremors is consistent with the scaling law of slow earthquakes. Plain Language Summary: Slow earthquakes are characterized by very slow underground deformation compared with regular (fast) earthquakes and are important for understanding the preparation period prior to large earthquakes. Tectonic tremors, which are a type of slow earthquakes, radiate tiny seismic waves with frequencies of several Hz, occur episodically and densely in space and time, and may last for long durations of up to several hundred seconds, which is much longer than the durations of fast earthquakes of equivalent magnitude. In this study, we detect and differentiate tectonic tremors from fast earthquakes and anthropogenic events. We do this using a set of event features, without relying on subjective criteria. The durations of the detected tremors range from 0.3 to ∼100 s, and they appear consistent with a previously proposed scaling relationship for slow earthquakes. This result suggests that fast earthquakes and slow earthquakes have different physical mechanisms. Key Points: We compile a more complete tectonic tremor catalog for western Japan using a clustering method based on event featuresEvent duration, newly defined using energy radiation, clearly separates tectonic tremors from fast earthquakesTectonic tremors, ranging in duration from 0.3 to 100 s, are consistent with the scaling law of slow earthquakes [ABSTRACT FROM AUTHOR]

We consider 3-component records of the magnetic field strength with a time step of 1 min at 153 stations of the INTERMAGNET network for 31 years, 1991–2021. Data analysis is based on the calculation of pairwise correlation coefficients between wavelet coefficients in successive time windows 1 day long (1440 min counts). To describe the state of the magnetic field, the maxima of the average values of all pairwise correlation coefficients between stations were chosen, calculated over all detail levels of the wavelet decomposition and over all components of the magnetic field strength vector. The daily time series of such maxima is called wavelet correlation. The division of the network stations into 7 clusters is considered, and a time series of wavelet correlations is calculated for each cluster. In a sliding time window with a length of 365 days, correlation measures of synchronization of wavelet correlations from different clusters are calculated, which are compared with the strongest earthquakes with a magnitude of at least 8.5. For the global time series of wavelet correlations, the method of influence matrices is used to study the relationship between the maximum correlation responses to a change in the length of the day and a sequence of earthquakes with a magnitude of at least 7. As a result of the analysis, precursor effects are identified, and the important role of the Maule earthquake in Chile on February 27, 2010 in the behavior of the response of magnetic field for the preparation of strong seismic events is shown. [ABSTRACT FROM AUTHOR]

The objective of this study is to present a method for developing fragility curves for soil liquefaction that align with seismic hazards using Monte Carlo simulation. This approach can incorporate all uncertainties and variabilities in the input parameters. The seismic parameters, including earthquake magnitude (M) and associated peak ground acceleration (PGA), are jointly considered for the liquefaction assessment. The liquefaction potential and the resulting damages obtained by this method are more realistic. A case study is conducted using data from a sand-boil site in Yuanlin, Changhua County, where liquefaction occurred during the 1999 Chi-Chi earthquake in Taiwan. The findings indicate that the liquefaction potential index, IL, the post-liquefaction settlement, St, and the liquefaction probability index, PW, are all appropriate parameters for assessing liquefaction damages. The fragility curves for soil liquefaction developed through this method can support the performance-based earthquake engineering (PBEE) approach, provide guidance for liquefaction evaluation to the Taiwan Earthquake Loss Estimation System (TELES), and serve as a foundation for scenario simulation and an earthquake early warning system for liquefaction damages. [ABSTRACT FROM AUTHOR]

This case study evaluated the liquefaction risk and application of vibro-compaction for soil improvement in a construction project site on Saadiyat Island, Abu Dhabi, UAE. Abu Dhabi is designated as Zone 0 according to the Uniform Building Code (UBC-97), and we discuss the design criteria for vibro-compaction that were adopted to mitigate the liquefaction risk, the trials conducted to establish the application criteria for vibro-compaction, and the general practices related to vibro-compaction. Specific studies conducted in Abu Dhabi Emirate indicate that the seismicity in the region is low, and the probability of liquefaction is very limited. However, during the pre-project soil investigation phase, the analysis of potential soil liquefaction indicated that certain examined areas have the potential to undergo liquefaction. The liquefaction potential was assessed based on a combination of safety factors obtained for an earthquake with a magnitude Mw = 6 and the corrected cone tip resistance (qc). The acceptability criteria for improved soil are based on cone penetration test (CPT) results. The target qc is accepted as 2.7 MPa and the treatment depth would be a minimum of − 3.5 m. A field trial was conducted to determine the optimal compaction grid spacing that meets the specified acceptance criteria and aligns with the project's design criteria. Based on the trial evaluation, a vibro-compaction grid spacing of 4 × 4 m was appropriate. Consequently, a total of 4125 points at the construction site underwent vibro-compaction. [ABSTRACT FROM AUTHOR]

The complexity of strike-slip fault segmentation affects the initiation, propagation, and termination of earthquake ruptures and the earthquake magnitude. Studying the fault geometry, kinematics, and segmentation provides fundamental knowledge for mitigating earthquake hazards along faults. The Zemuhe, Daliangshan, and Xiaojiang Faults intersect along the eastern boundary of the Tibetan Plateau in the area from Ningnan in Sichuan Province to Qiaojia in Yunnan Province. Although few large earthquakes have occurred on these faults, the relationships between the intersections of these three faults and earthquake rupture behavior in this region are poorly constrained. The interpretation of aerial photographs and detailed field surveys revealed the geometric pattern and fault kinematics in the area of intersection. The distribution patterns and focal depths near the faults were obtained via analysis of seismic data in the area of intersection. The northern segment of the Xiaojiang Fault deviates approximately 25° northwest of Qiaojia, forming a conspicuous bend. The Xiaojiang Fault continues to extend southeast of the Ningnan Basin, where it intersects with the southern segment of the Zemuhe Fault, forming a pullapart basin approximately 4.5 km wide. The bend and Ningnan pull-apart basin mark the segmented boundary between the Zemuhe Fault and the Xiaojiang Fault, which may prevent the propagation of large earthquake ruptures along the eastern boundary fault. Moreover, the lack of obvious geometric complexity between the Daliangshan Fault and Xiaojiang Fault might hinder the prevention of earthquake rupture propagation. Additionally, our results suggest that different earthquake prevention and disaster reduction measures should be taken for different cities in the region. [ABSTRACT FROM AUTHOR]

This study introduces the long‐range Ising model from statistical mechanics to the performance‐based earthquake engineering (PBEE) framework for regional seismic damage analysis. The application of the PBEE framework at a regional scale involves estimating the damage states (DSs$DS\mathrm{s}$) of numerous structures, typically performed using fragility function‐based stochastic simulations. However, these simulations often assume conditional independence or employ simplistic dependency models among the DSs$DS\mathrm{s}$ of structures, leading to significant misrepresentation of regional risk. The Ising model addresses this issue by converting the available information on binary DSs$DS\mathrm{s}$ (safe or failure) into a joint probability mass function, leveraging the principle of maximum entropy. The Ising model offers two main benefits: (1) it requires only the first‐ and second‐order cross‐moments, enabling seamless integration with the existing PBEE framework, and (2) it provides meaningful physical interpretations of the model parameters, facilitating the uncovering of insights not apparent from data. To demonstrate the proposed method, we applied the Ising model to 156 buildings in Antakya, Turkey, using post‐hazard damage evaluation data, and to 182 buildings in Pacific Heights, San Francisco, using simulated data from the Regional Resilience Determination tool. In both instances, the Ising model accurately reproduces the provided information and generates meaningful insights into regional damage. The study also investigates the change in Ising model parameters under varying earthquake magnitudes, along with the mean‐field approximation, further facilitating the applicability of the proposed approach. [ABSTRACT FROM AUTHOR]

Interseismic coupling maps and, especially, estimates of the location of the fully coupled (locked) zone relative to the trench, coastline, and slow slip events are crucial for determining megathrust earthquake hazard at subduction zones. We present an interseismic coupling inversion that estimates the locations of the upper and lower boundaries of the locked zone, the lower boundary of the deep transition zone, and downdip gradient of creep rate in the transition from locked to freely creeping in the downdip transition zone. We show that the locked zone at Cascadia is west of the coastline and 10 km updip of the slow slip zone along much of the margin, widest (25–125 km, extending to ∼19 km depth) in northern Cascadia, narrowest (0–70 km) in central Cascadia, with moment accumulation rate equivalent to a Mw 8.71 and Mw 8.85 earthquake for 300‐ and 500‐year earthquake cycles. We find a steep gradient in creep immediately below the locked zone, indicative of propagating creep, along the entire margin. At Nankai, we find three distinct zones of locking (offshore Shikoku, offshore southeast Kii peninsula, and offshore Shima peninsula) with a total moment accumulation rate equivalent to a Mw 8.70 earthquake for a 150‐year earthquake cycle. The bottom of the locked zone is nearly under the coastline for all three locked regions at Nankai and is positioned 0–5 km updip of the slow slip zone. In contrast with Cascadia, creep rate gradients below the locked zone at Nankai are generally gradual, consistent with stationary locking. Plain Language Summary: Maps of where faults are not moving (the locked zone) can be used to assess future earthquake size and impacts on nearby communities due to ground shaking and tsunamis. Slow slip events, occurring below and around the locked zone, may transfer stress from deeper on the fault to the locked zone and increase earthquake potential. We use measurements of movement of the surface of the earth and models of how surface movements reflect to slip on a fault in order to locate the boundaries of the locked zone in relation to the coastline, the trench, and slow slip events at Cascadia and Nankai subduction zones. We find that a release of slip accumulated in the current Cascadia and Nankai locked zones would result in earthquakes of magnitude Mw 8.71–8.85 and Mw 8.70, respectively. We also find evidence that the depth to the bottom edge of the locked zone at Cascadia and in some areas of Nankai may have shallowed since the last earthquake. Our model provides better estimates and realistic ranges for the location of the boundaries of the locked zone which can inform earthquake rupture, ground motion, and tsunami models. Key Points: We developed a coupling zone boundary inversion with a forward model of shallow creep at constant stress and deep updip‐propagating creepThe locked zone accounts for 48% of the interseismic moment accumulation rate at Cascadia and 46% at NankaiWe infer steep creep rate gradients, indicative of updip‐propagating creep, at Cascadia and below Shikoku and Shima peninsula at Nankai [ABSTRACT FROM AUTHOR]

Artificial intelligence (AI) seismology has witnessed enormous success in a variety of fields, especially in earthquake detection and P and S‐wave arrival picking. It has become widely accepted that DL techniques greatly help routine seismic monitoring by enabling more accurate picking than traditional pickers like STA/LTA. However, a completely automatic AI‐driven earthquake monitoring framework has not been reported due to the concerns of potential false positives using DL pickers. Here, we propose a novel AI‐facilitated near real‐time monitoring framework using a recently developed deep learning (DL) picker (EQCCT) that has been deployed in the Texas seismological network (TexNet). For the West Texas area, TexNet's seismic monitoring relies on the EQCCT picker to report earthquake events. For earthquakes with a magnitude above two, the picks are further validated by analysts to output the final TexNet catalog. Due to the fast‐increasing seismicity caused by continuing oil&gas production in West Texas, this AI‐facilitated framework significantly relieves the workload of TexNet analysts. We show the mean absolute error (MAE) of automatic magnitude estimation for the magnitude‐above‐two earthquakes is smaller than 0.15 in West Texas and MAEs of hypocenter locations within 2.6 km in both distance and depth estimates. This research provides more evidence that DL pickers can play a fundamental role in daily earthquake monitoring. Plain Language Summary: AI has been a significant part of almost every aspect of our life. However, it is not widely accepted that AI can be a game changer in geoscience. In this work, we provide a compelling example that AI can significantly lower the overload of earthquake analysts in everyday work and boost our earthquake detectability, thereby enhancing our understanding of earthquake statistics, physics, and potential nucleation mechanisms. In a nutshell, AI has already been demonstrated to be successful in earthquake analysis but never in real‐time monitoring, which requires a high success rate and zero tolerance to large‐earthquake detection errors. Here, we show that AI‐assisted earthquake monitoring workflow can be almost 100% accurate for moderate‐to‐large earthquakes. Key Points: We propose an AI‐facilitated near real‐time monitoring framework that has been deployed at TexNet using a recently developed deep learning (DL) pickerDue to the fast‐increasing seismicity in West Texas, this AI‐facilitated framework significantly relieves the workload of TexNet analystsThe mean absolute error (MAE) of automatic magnitude estimation for the magnitude‐above‐two earthquakes is smaller than 0.15 in West Texas [ABSTRACT FROM AUTHOR]

The East Anatolian fault in Turkey exhibits along-strike rupture segmentation, typically resulting in earthquakes with moment magnitude (Mw) up to 7.5 that are confined to individual segments. However, on 6 February 2023, a catastrophic Mw 7.8 earthquake struck near Kahramanmaraş (southeastern Turkey), defying previous expectations by rupturing multiple segments spanning over 300 km and overcoming multiple geometric complexities. We explore the mechanics of successive single- and multi-segment ruptures using numerical models of the seismic cycle calibrated to historical earthquake records and geodetic observations of the 2023 doublet. Our model successfully reproduces the observed historical rupture segmentation and the rare occurrence of multi-segment earthquakes. The segmentation pattern is influenced by variations in long-term slip rate along strike across the kinematically complex fault network between the Arabian and Anatolian plates. Our physics-based seismic cycle simulations shed light on the long-term variability of earthquake size that shapes seismic hazards. [ABSTRACT FROM AUTHOR]

The purpose of this study is to systematically investigate the segmental seismicity features of the Zhangjiakou-Bohai tectonic belt to understand the characteristics of the seismic activity in this tectonic area and identify potential sources of strong earthquake hazard. From the collected seismic data, we first determined the minimum completeness magnitude by combining qualitative and quantitative methods, such as the detection rate function, maximum curvature (MAXC) method, goodness of fit (GFT) method and magnitude-rank method. We used the stochastic declustering method based on the space-time ETAS model to obtain the background seismicity. We then implemented the accelerating moment release (AMR) model, the Ogata-Katsura 1993 (OK1993) model, the moment ratio (MR) model and the Region-Time-Length (RTL) algorithm. Finally, we analyzed the spatial migration of strong earthquakes. The completeness magnitude of the earthquake sequence does not significantly change with time, with the minimum completeness magnitude being 2.0 for the Zhangjiakou-Bohai tectonic zone. The results provided by the aforementioned seismic activity models allow us to detect some differences between sectors of the tectonic belt. The Zhangjiakou and Tangshan segments show a higher level of seismic hazard compared to the others, which have little chance of a strong earthquake occurring (weak release of seismic energy). The b value of the Zhangjiakou segment shows a stepwise downward trend, reflecting the gradual increase of stress accumulation level, and the hazard of moderate-strong earthquakes is increasing. Compared with the Tangshan and Penglai segments, the Zhangjiakou and Beijing sectors have a slightly higher MR index, which means that the rate of earthquake occurrence is increasing and thus the hazard of moderate to strong earthquakes. According to the RTL value, the deviation of seismic activity in the Zhangjiakou and Tangshan segments is relatively high, and there is a possibility of moderate to strong earthquakes in the future. Based on the results obtained from various seismicity models and the migration law of strong earthquakes, we can say that the overall seismic hazard for each sector of the Zhangjiakou-Bohai tectonic chain is low in terms of qualitative analysis. If anything, the Zhangjiakou segment, which is the section with the relatively high seismic hazard level, should require our attention in the future. [ABSTRACT FROM AUTHOR]

Detection and separation of the subtle post-seismic deformation signals associated with moderate magnitude earthquakes from interferometric synthetic aperture radar (InSAR) time-series is often challenging. Singular spectrum analysis (SSA) is a statistical non‐parametric technique used to decompose and reconstruct signals from complex time-series data. We show that the SSA analysis effectively distinguished the post-seismic signal associated with the 2019 M w 6 Mirpur earthquake from periodic and noise components. The SSA-derived post-seismic deformation signal is smoother and fits better to an exponential model with a decay time of 34 d. The post-seismic deformation is confined to the southeast of the rupture area and lasted for ∼90 d following the main shock. Inversion of the post-seismic deformation suggests an afterslip mechanism with a maximum slip of ∼0.07 m on the shallow, updip portions of the Main Himalayan Thrust. The 2019 Mirpur earthquake and afterslip together released less than 12 per cent of the accumulated strain energy since the 1555 Kashmir earthquake and implies continued seismic hazard in the future. [ABSTRACT FROM AUTHOR]

Seismic and tsunami hazard modelling and preparedness are challenged by uncertainties in the earthquake source process. Important parameters such as the recurrence interval of earthquakes of a given magnitude at a particular location, the probability of multifault rupture, earthquake clustering, rupture directivity and slip distribution are often poorly constrained. Physics-based earthquake simulators, such as RSQSim, offer a means of probing uncertainties in these parameters by generating long-term catalogues of earthquake ruptures on a system of known faults. The fault initial stress state in these simulations is typically prescribed as a single uniform value, which can promote characteristic earthquake behaviours and reduce variability in modelled events. Here, we test the role of spatial heterogeneity in the distribution of the initial stresses and frictional properties on earthquake cycle simulations. We focus on the Hikurangi–Kermadec subduction zone, which may produce M w > 9.0 earthquakes and likely poses a major hazard and risk to Aotearoa New Zealand. We explore RSQSim simulations of Hikurangi-Kermadec subduction earthquake cycles in which we vary the rate and state coefficients (a and b). The results are compared with the magnitude-frequency distribution (MFD) of the instrumental earthquake catalogue and with empirical slip scaling laws from global earthquakes. Our results suggest stress heterogeneity produces more realistic and less characteristic synthetic catalogues, making them particularly well suited for hazard and risk assessment. We further find that the initial stress effects are dominated by the initial effective normal stresses, since the normal stresses evolve more slowly than the shear stresses. A heterogeneous stress model with a constant pore-fluid pressure ratio and a constant state coefficient (b) of 0.003 produces the best fit to MFDs and empirical scaling laws, while the model with variable frictional properties produces the best fit to earthquake depth distribution and empirical scaling laws. This model is our preferred initial stress state and frictional property settings for earthquake modelling of the Hikurangi–Kermadec subduction interface. Introducing heterogeneity of other parameters within RSQSim (e.g. friction coefficient, reference slip rate, characteristic distance, initial state variable, etc.) could further improve the applicability of the synthetic earthquake catalogues to seismic hazard problems and form the focus of future research. [ABSTRACT FROM AUTHOR]

Moderate magnitude earthquakes and seismic sequences frequently develop on fault systems, but whether they are linked to future major ruptures is always ambiguous. In this study, we investigated a seismic sequence that has developed within a portion of the stretching region of the Apennines in Italy where moderate to large earthquakes are likely to occur. We captured a total of 2039 aftershocks of the 2023 September 18, M w 4.9 earthquake occurred during the first week, by using machine-learning (ML) based algorithms. Aftershocks align on two 5–7 km long parallel faults, from a length that exceeds what is expected from the main shock magnitude. The segments are ramping at about 6 km depth on closely spaced N100 striking 70 N dipping planes, at a distance of some kilometres from the main shock hypocentre. Our results indicate that even moderate magnitude events trigger seismicity on a spread set of fault segments around the main shock hypocentre, revealing processes of interaction within the crustal layer. The possibility that larger earthquakes develop during seismicity spread is favoured by pore pressure diffusion, in relation with the closeness to criticality of fault segments. Based on the very rapid activation of seismicity on the entire system and a back-front signal from the hypocentre of the main event, we infer that fluid pressure, initially high within the crustal layer, rapidly dropped after the main shock. Our study reinforces the importance of timely extracting information on fault geometry and seismicity distribution on faults. ML-based methods represent a viable tool for semi-real-time application, yielding constraints on short-time forecasts. [ABSTRACT FROM AUTHOR]

In the present study, a hypothetical earthquake of magnitude 8.5 has been simulated using the modified hybrid technique. Existing hybrid technique, as the name suggests, is the blend of two already existing simulation techniques, i.e. composite source technique and the envelope technique. In the present modified technique, site response functions and high-frequency decay parameter (kappa factor) have also been introduced in the existing hybrid technique. The waveforms have been simulated at more than 430 points using the calculated site response or transfer function estimated at 50 recording stations situated in the central seismic gap (CSG) region of Himalaya. Peak ground acceleration (PGA) and duration parameters have been estimated. Calculated PGA values helped estimating in the corresponding intensity for those PGA values at various stations. With the help of these PGA and intensity values, the scenario hazard map has been prepared for central seismic gap (CSG) region of Himalaya. It has been found that the stations situated close to rupture initiation point is ≥ 1 g. The estimated PGA values have been compared with the PGA values of other studies. The earthquake has been simulated using three different rupture points The station having highest PGA values changed with rupture initiation point. The intensity values are correlated with the damage pattern of region and therefore relatively more useful for agencies involved in the mitigation of seismic hazard of the region. Accordingly, the synthetic intensity maps have been generated in the present study by converting PGA values into MMI values using an empirical relation. The comparison with the other studies shows an agreement with the other studies. This modified technique is independent aftershocks database and velocity-Q structure. This research work will help bringing light on the effect of site response functions and kappa factor. This kind of study can help in mitigate the earthquake hazard and design an earthquake-resistant structures and building for that particular area. [ABSTRACT FROM AUTHOR]

Two massive earthquakes hit Turkey on February 6, 2023. The first occurred at around 4 a.m. local time and the other at around midday. The quakes affected almost ten cities and around thirteen million people. Unfortunately, the number of casualties increased with time. These earthquakes reminded us of the importance of the determination of the magnitude of an earthquake in a couple of minutes with as high accuracy as possible, which is vital for the people who live in the epicenter area. Governmental institutes must announce the magnitude of an earthquake quickly if it is huge to start a response action. This study shows the quality and efficiency of the technique that calculates the P-wave moment magnitude (Mwp) using local (strong-motion records), regional and teleseismic (velocity records) waveforms recorded at seismic stations located at different epicentral distances. The disadvantage of determining the time window for calculations was resolved with this study using calculated P-wave velocity and theoretically determined S-wave arrival times depending on the regional and teleseismic waveforms' onset and epicentral distance. The Mwp magnitude has been calculated as 7.9 using regional and teleseismic waveforms for events one and two, whereas 7.7 and 7.6 with strong-motion waveforms for events one and two, respectively, are compatible with Global Centroid Moment Tensor (GCMT) magnitude 7.8 and 7.7 for events one and two. The results of this study clearly show that an earthquake research institute should evaluate all the seismic waveforms recorded at different epicentral distances to get a confidential magnitude value considering destructive events, which is possible with data sharing through global networks at present. [ABSTRACT FROM AUTHOR]

The Chile subduction zone is known to host megathrust earthquakes. This study investigates the near‐field co‐seismic ionospheric perturbations (CIP) associated with recent large to great, shallow depth (22–25 km) earthquakes that occurred in the Chile subduction zone. These earthquakes are (a) 16 September 2015, Mw 8.3 (EQ1) (b) 03 April 2014, Mw 7.7 (EQ2) (c) 01 April 2014, Mw 8.2 (EQ3) (d) 02 January 2011, Mw 7.1 (EQ4), and (e) 27 February 2010, Mw 8.8 (EQ5). Using the Global Navigation Satellite System (GNSS) measured total electron content (TEC), we found that despite the lower magnitude of EQ3 than EQ1 and EQ5, the CIP observed during EQ3 had higher amplitudes than that of EQ5 and EQ1. The amplitude of CIP also depends on non‐seismic parameters in addition to the concerning earthquake magnitude. The comparison of relative CIP amplitudes, in light of the non‐seismic parameters of the geomagnetic field and satellite geometry indicates that background electron density (due to different local times of earthquake occurrence) might contributed to CIP amplitudes. We believe that this thorough analysis leads to a better understanding of non‐seismic factors that can largely influence the CIP amplitudes apart from the earthquake magnitudes. Key Points: GNSS‐TEC measured co‐seismic ionospheric perturbation during the shallow depth earthquakes in Chile‐subduction zoneInvestigating the role of seismic and non‐seismic parameters in manifesting co‐seismic ionospheric perturbationEstimating the dependency between the co‐seismic ionospheric perturbation amplitude and earthquake magnitude [ABSTRACT FROM AUTHOR]

S-net is a seafloor observation network for earthquakes and tsunamis around the Japan Trench, comprising 150 observatories with seismometers and pressure gauges. The region has been known to experience massive earthquakes, and several magnitude 6 and 7 class earthquakes have occurred after the network was established in 2016. This study constructed ground motion prediction equations (GMPEs) for horizontal peak ground accelerations (PGAs) and peak ground velocities (PGVs) using the S-net data and revealed that the GMPEs can be used to predict the PGAs and PGVs at the land stations where measured S-wave velocities are available. We used a relatively short time window of the S-net records from the viewpoint of earthquake early warning but included S waves. Data from earthquakes of magnitudes between Mw 5.5 and Mw 7.4 were used. The construction of the GMPEs was achieved in two steps. First, regression analysis was conducted for each event data, and mean site residual was obtained over the available records at each S-net site. Second, the data were adjusted by the mean site residuals, and stratified regression analysis, which decouples the source and path factors, was performed. Finally, we applied the GMPEs to predict PGAs and PGVs at the KiK-net sites on land. We determined that the residuals at the KiK-net sites were systematically biased with Vs30 (average S-wave velocity in the upper 30 m). We obtained correction factors for the bias and demonstrated that the PGAs and PGVs at the KiK-net sites could be predicted reasonably well. [ABSTRACT FROM AUTHOR]

In November 1815, the deadliest "natural" disaster in Balinese history was caused by the exceptional combination of multiple natural hazards that occurred simultaneously and cascaded in the present-day province of Buleleng. This major disaster, which is thought to have claimed more than 10,000 lives, has never been scientifically analyzed. The study conducts an in-depth analysis of this cascading disaster, from the root causes and chronology of natural hazards to their environmental and societal effects, by thoroughly examining all available written sources about this event, whether colonial or Indonesian. Seven months after the Tambora eruption, a magnitude 7.3 earthquake, which occurred in the Bali Sea off the northern coast of the island, triggered a very large landslide on the northern flank of the Buyan-Bratan caldera. The initial mass movement evolved into a cohesive debris flow that reached the sea after traveling up to twenty kilometers through Banyumala River Valley and Singaraja City downstream. According to historical accounts, fifteen villages were buried or devastated by the debris flow. The large volume of sediment entering the sea triggered a local tsunami along Buleleng's coast. This geohistorical approach offers a comprehensive overview of various sources describing Singaraja's situation before the crisis, the hazard succession, the cascading hazard intensities, and the short- to long-term impacts on Buleleng. Based on the written sources, Bali took around fifteen years to recover from the 1815 disasters. [ABSTRACT FROM AUTHOR]

Surface topographic irregularities can alter ground motion. In this study, we investigated the influence of various topographic factors such as relative elevation, slope angle, and curvature on ground-motion amplification. A finite element analysis with absorbing boundary layer was performed using actual topographic data and ground motion data from earthquakes of magnitude 3.8–9 recorded in Japan. To identify the effect of wave velocity on ground motion amplification, we considered the variability in topography and three sets of shear and longitudinal wave velocities by considering five cross-sectional profiles for the topographic models in the numerical analyses. We demonstrate that the topographic amplification factor, which is the ratio of the estimated spectral acceleration on the surface to the median spectral acceleration within the entire surface domain, is significantly influenced by curvature and relative elevation. Furthermore, we have proposed models that estimate ground-motion amplification using the two topographic factors—curvature and relative elevation—as variables. [ABSTRACT FROM AUTHOR]

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 M 6.2. 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. [ABSTRACT FROM AUTHOR]

The focal mechanism solution is one of the important focal parameters for exploring fault activity and studying regional stress distribution and it has a wide range of applications. The geological structure of the Sichuan- Yunnan region in China is complex, with frequent earthquakes and abundant historical observation data, making it one of the popular areas of concern for scholars. This study utilizes the high-precision community velocity model v2.0 of southwest China, obtained through joint inversion based on multiple data methods. The Cut-And- Paste (CAP) method was employed to fit and invert the observed waveforms of 1475 events with ML ≥ 3.5 in the Sichuan-Yunnan region from January 2012 to December 2022, thereby constructing a catalog of double-couple focal mechanisms. By comparing the focal mechanism inversion results of small earthquakes with those from multiple one-dimensional velocity models and conducting comparative statistical analysis on events below magnitude 4, it has been demonstrated that the model used in this study provides a better fit than onedimensional models. This contributes to establishing the lower magnitude limit for producing deeper focal mechanism solutions. This study compares the results of larger magnitude earthquakes in the catalog with those published by the Global Centroid-Moment Tensor (GCMT) project and smaller magnitude earthquakes with the catalog released by the Institute of Earthquake Forecasting, China Earthquake Administration. These comparisons serve to validate the accuracy of the catalog results. Leveraging the high-resolution velocity model, this catalog has re-examined the historical earthquake focal mechanism catalog of the Sichuan-Yunnan region. The inversion has yielded reliable results for smaller magnitudes and a greater number of events, providing additional data and support for understanding the regional stress field, active faults, the mechanisms of large earthquake genesis, and earthquake prediction efforts. Consequently, this enhances the depth of scientific research in the Sichuan-Yunnan region. [ABSTRACT FROM AUTHOR]