Abstract Although the Permian Basin of Texas and New Mexico is one of the world’s most important hydrocarbon-producing regions, ongoing earthquakes triggered by industrial activities have led to regulatory restrictions in parts of the basin. Curtailment of injection into saline formations above geologic basement within regulated seismic response areas (SRAs) have resulted in declined monthly local magnitude (ML) 3+ earthquakes since 2021 but problematic induced earthquakes still occur. There is scientific consensus that deep injection is a primary causative agent, but significant unanswered questions remain including: the geometry and magnitude of anthropogenic stressing stemming from injection at all levels, the permeability structure of the injection reservoirs, and the connectivity to seismogenic faults. Curtailment of deep injection has caused operators to prioritize increasing injection into shallow saline reservoirs which threatens the surface environment by leakage along old wellbores, produces invasion of water into oil-productive zones, and increases drilling risk. Shallow injection reservoirs host dense fault networks which may act as anisotropic pore pressure conduits. Using a high-quality ~1,500 km2 3D seismic reflection dataset that images a key portion of the highly seismogenic NCR SRA, we provide an interpretation and characterization of fault systems at all levels. There are three distinct levels of faulting: i) intra-basement (IB); ii) basement-rooted (BR); and iii) shallow, strata-bound faults (SSB). IB are low-to moderately-dipping (~20–45°) thrust faults, which are truncated by the Great Unconformity. BR faults are moderate-to high-angle reverse and strike-slip faults (~50–90°), which offset the Great Unconformity and overlying Paleozoic strata including deep injection strata. SSB are steeply-dipping (~60–80°) elongate, narrow graben, which cut upper-Permian age units, including shallow injection strata.

In 2021, the seismic monitoring in Kazakhstan was conducted by two organizations: State Enterprise “Seismological Experience‑Methodical Expedition” of the Committee of Science of the Ministry of Education and Science of the Republic of Kazakhstan and the Branch “Institute of Geophysical Research” of the Republican State Enterprise “National Nuclear Centre” of the Ministry of Energy of the Republic of Kazakhstan. The paper presents detailed information on seismic observation networks and characteristics of the joint catalogue for Kazakhstan earthquakes compiled by data of two organizations. It includes 453 earthquakes with energy class KR =6.6–11.7. The strongest earthquake within the considered territory occurred on January 8, 2021, KR =11.7, MPVA=5.2. Its epicenter was located on the territory of China in the high mountain part of inner Tien Shan. On so‑ called “Northern Tien Shan” territory, 361 earthquakes with energy class KR≥ 6.6 were recorded. The reoccurrence graphs and the calculated parameters of seismic regime are given, the focal mechanisms of earthquakes with KR≥9 and parameters of strong motion records are described for 18 earthquakes. In 2021, seismic networks recorded 4535 mining explosions on the territory of Kazakhstan as well as several induced earthquakes at the regions of liquid mineral production deposits.

The optimization of seismic resilience in steel moment-resisting frames (SMRFs) has driven extensive research into passive energy dissipation systems, particularly rotational friction dampers (RFDs). This study introduces a novel hybrid optimization framework that simultaneously determines the optimal placement and design parameters of RFDs in SMRFs. A sensitivity analysis of key RFD parameters, including frictional moment and rigid beam length, highlights their influence on seismic performance. The optimization problem is formulated based on the seismic energy dissipation concept, employing a modified binary and real-coded particle swarm optimization (BRPSO) algorithm. The study examines both 6- and 10-story SMRFs under artificial earthquake records, incorporating soil-structure interaction (SSI) effects to enhance accuracy. The results reveal that the optimal distribution of RFDs significantly reduces structural hysteretic energy and inter-story drift while improving energy dissipation efficiency. A comparative analysis shows that, for both SMRF configurations, an increase in the number of RFDs beyond the optimal threshold yields diminishing benefits in seismic mitigation. The proposed framework not only enhances structural resilience but also minimizes construction costs by ensuring an efficient damper layout. These findings provide valuable insights for designing cost-effective and high-performance seismic protection strategies for mid- to high-rise structures.

Numerical Optimization–Based Generation of Artificial Earthquakes for Seismic Analysis

Abstract Fracking and deep wastewater injection-induced seismicity in Oklahoma has led to over 1000 Mw>3 earthquakes over the last 16 yr, four of which had Mw>5. Furthermore, the 3 September 2016, Mw 5.8 Pawnee, Oklahoma, earthquake was the first induced event worldwide, that the authors are aware of, that triggered liquefaction, which raises concerns regarding liquefaction risk posed by induced earthquakes. To address these concerns, Quick et al. (2025) developed a new triggering model for evaluating the regional liquefaction hazard in Oklahoma, Texas, and Kansas (OTK) from induced earthquakes. As part of model development and validation, sites were characterized where liquefaction manifestations were and were not observed following the Pawnee earthquake. Liquefaction potential at each site was estimated using a new OTK-induced seismicity-specific liquefaction triggering model, as well as several models commonly used to evaluate liquefaction potential for tectonic earthquakes. Estimates were compared with field observations following the Pawnee event to assess the efficacy of these models. This analysis showed that at most sites, the induced seismicity-specific model more accurately predicted liquefaction severity than did models developed for tectonic earthquakes, which tended to overpredict liquefaction severity.

Abstract Critical equipment in nuclear power plant auxiliary buildings such as control cabinets, panels, transformers, and diesel generators often malfunction before structural damage occurs, demanding rapid post‐earthquake inspection prioritization. However, direct walkdown inspection or dense sensor networks are impractical due to restricted accessibility in radiological zones and the high costs associated with maintenance. To address this, we propose a residual convolutional network‐based virtual sensing framework that supports urgent inspection prioritization by predicting acceleration at 139 locations from a single high‐quality seismometer. The model employs six residual blocks with progressively downsized kernels to capture multi‐scale features, while skip connections prevent vanishing gradients. Trained on artificial earthquakes with 10 dB noise and validated against unseen Next Generation Attenuation‐West 2 ground motions matched to Nuclear Regulatory Commission Regulatory Guide 1.60 and Korean uniform‐hazard spectra, the model achieves a maximum mean absolute percentage error of 0.44%–0.59% for noise‐free case and ≤4.23% at 10 dB, demonstrating robust generalization. The resulting rapid, noise‐tolerant virtual sensor network enables actionable equipment‐level decision making in nuclear facilities at a fraction of conventional monitoring cost.

Response spectra are helpful in the structural engineering practice for the design with earthquake as an extreme load case. However, it is restricted to the linear analysis, except for the plastic behavior. The linear analysis uses a single stiffness only, and by this, the low-level nonlinearities, as the opening and closure of cracks in reinforced concrete structures, are neglected. In this paper, we investigate single-degree-of-freedom systems with two linear elastic states. The response of the piecewise linear elastic structure is compared to the linear response for artificial earthquake accelerograms confined to a design response spectrum. The analysis shows that a high difference in the stiffnesses of the two states may result in a considerable increase in the response. At the same time, states with small relative differences in their stiffness have a maximum response below or close to the response of the linear system. Thus, the neglect of the low-level nonlinearity, as the opening and closing of a crack does not affect the assessment of the structure.

SUMMARY This paper investigates the seismic activity and velocity structure in the Three Gorges Reservoir (TGR) region using high-quality traveltime data from an extensive seismic observation network. The primary goal is to understand the relationship between the 3-D velocity structure and seismicity within the reservoir area. We employed advanced inversion techniques to develop detailed 3-D models of the P- and S-wave velocities and analysed the focal mechanisms of significant seismic events. Our results reveal that there are substantial lateral variations in the upper crustal velocity structure, with high-velocity zones in the northeastern region of Badong and lower velocities in the Zigui Basin (ZGB). The sedimentary layers in the ZGB are 6–8 km thick, and low S-wave velocity anomalies extend from this depth and are correlated with the Triassic formations. The seismic activity patterns show that the earthquakes in the Badong region were concentrated along three east–west trending belts within the core of an anticline. These patterns suggest that the geological structures and fluid infiltration significantly influence the seismicity. In particular, the M5.1 Badong earthquake occurred at the boundary of a high-velocity zone and was associated with a seismic belt extending from shallow to deeper depths. The results of this study highlight the complex interactions between rock heterogeneity, fault dynamics and fluid effects, providing a comprehensive analysis of reservoir-induced seismicity. This work provides a better understanding of the physical mechanisms driving seismic activity in large reservoir systems and provides insights relevant to seismic hazard assessment and reservoir management.

ABSTRACTAdvanced seismicity monitoring is needed for CO2 sequestration monitoring. Current regulator practices (so‐called traffic light systems—TLS) are limited to mitigate public hazards and associated risks caused by induced seismicity. Such seismicity is often associated with slip on larger faults below the reservoir. We propose an advanced seismic monitoring strategy that not only accounts for felt seismicity but also targets seismicity in the seal and reservoir. This novel concept of tiered seismicity criteria for an advanced seismic monitoring strategy is governed by a storage site's specific geological properties (underburden, reservoir and seal). These observed seismicity criteria can be set by the regulator or operator to develop a corresponding and fit for purpose system that further manages induced seismicity to ensure seal integrity and storage longevity.

Deciphering groundwater potential zones using integrated approach of remote sensing, GIS, and AHP in a reservoir-induced seismicity (RIS) region in western India

Abundant and well-documented seismic data have shown that there is a significant correlation between the earthquakes and water impoundment in the Three Gorges Reservoir Region and hydraulic fracturing operations on Well EYY1 and Well EYY2 within this area were conducted to stimulate the shale gas. Monitoring detected numerous induced microseismic events during these industrial activities. However, discriminative analysis between reservoir-induced seismicity and hydraulic fracturing induced seismicity remains conspicuously absent. This paper provides a case study in the Three Gorges Reservoir Region where water impoundment and hydraulic fracturing operation were simultaneously conducted in a certain time. Findings show that most of the micro and small earthquakes were induced by the impoundment of the Three Gorges Reservoir, and were mainly distributed along the Yangtze River and its branches during the year of 2016–2019. The emerging cluster of earthquakes in the Xiannvshan Fault area of the Three Gorges Reservoir Region was induced by hydraulic fracturing on Well EYY1 and Well EYY2, rather than by impoundment, and the relationship between seismicity observed and hydraulic fracturing activities belongs to the rapid-response type. The emerging cluster of earthquakes observed in the area are predominantly associated with rock fracturing processes controlled by pre-existing natural fractures and in-situ stress regimes, with no evidence suggesting fault reactivation induced by hydraulic fracturing operations.

Given that aging deterioration significantly influences the structural behavior of reinforced concrete (RC) nuclear power plant (NPP) structures, it is crucial to incorporate changes in the material properties of NPPs for accurate prediction of seismic responses. In this study, machine learning (ML) models for predicting the seismic response of RC NPP structures were developed by considering aging deterioration. The OPR1000 was selected as a representative structure, and its finite element model was generated. A total of 500 artificial ground motions were created for time history analyses, and the analytical results were utilized to establish a database for training and testing ML models. Six ML algorithms, commonly employed in the structural engineering domain, were used to construct the seismic response prediction model. Thirteen intensity measures of artificial earthquakes and four material properties were employed as input parameters for the training database. The floor response spectrum of the example structure was chosen as the output for the database. Four evaluation metrics were implemented as quantitative measures to assess the prediction performance of the ML models. This study used multiple input variables to represent the characteristics of the seismic loads and changes in material properties, thereby increasing the minimum required database size for ML model development. This increase may extend the time and effort required to construct the database. Consequently, this study also explored the possibility of reducing the minimum required database size and the prediction performance through input dimension reduction of the ML model. Numerical results demonstrated that the developed ML model could effectively predict the seismic responses of RC NPP structures, taking into account aging deterioration.

Освоение месторождений твердых полезных ископаемых на современном этапе происходит в постоянно усложняющихся горно-геологи­ческих и геомеханических условиях и сопровождается проявлением таких опасных геодинамических явлений, как горные удары, внезапные выбросы породы и газа, техногенные землетрясения, часто имеющие катастрофические последствия. В статье представлены результаты исследований динамических проявлений горного давления и удароопасности за период с января по ноябрь 2024 г. на полиметаллических рудниках Дальневосточного региона, включая Южное и Николаевское месторождения. Объектом анализа стала геомеханическая обстановка, характеризующаяся высокой интенсивностью сейсмоакустической активности и частыми проявлениями горного давления. Основное внимание уделено геомеханическому мониторингу с применением автоматизированной системы контроля горного давления (АСКГД) «Prognoz-ADS», обеспечивающей регистрацию параметров акустической эмиссии в диапазоне 0,5–12 кГц. Анализ данных позволил выявить пространственно-временные закономерности сейсмоакустической активности и определить ключевые факторы, влияющие на удароопасность. Установлено, что наибольшее число динамических проявлений связано с пересечением крупных тектонических разломов, таких как разлом «Рудный», с зонами разрывных нарушений, а также с накоплением сжимающих напряжений вблизи рудных тел. Напряженно-деформированное состояние массива Южного месторождения осложняется наличием оставленных целиков забалансовых руд, межэтажных целиков и непогашенного выработанного пространства, что создает условия для реализации горно-тектонических ударов. Предложены рекомендации по дальнейшему совершенствованию системы мониторинга и управления рисками, связанными с динамическими проявлениями. Выводы подчеркивают необходимость комплексного подхода, включающего инструментальный мониторинг, моделирование напряженно-деформированного состояния и регулярный прогноз удароопасности. Эти меры направлены на повышение безопасности ведения горных работ и минимизацию рисков на месторождениях, характеризующихся высокой сейсмоакустической активностью. he development of solid mineral deposits at the present stage takes place with an ever-increasing complexity of mining, geological and geomechanical conditions and is accompanied by the manifestation of such dangerous geodynamic phenomena as mountain impacts, sudden emissions of rock and gas, man-made earthquakes, often with catastrophic consequences. The article presents the results of studies of dynamic manifestations of rock pressure and impact hazard for the period from January to November 2024 at polymetallic mines in the Far Eastern region, including the Yuzhnoye and Nikolaevskoye deposits. The object of the analysis was the geomechanical situation, characterized by a high intensity of seismic activity and frequent manifestations of mountain pressure. The main attention is paid to geomechanical monitoring using the “Prognoz-ADS” automated mountain pressure monitoring system, which records acoustic emission parameters in the range of 0.5–12 kHz. Data analysis made it possible to identify spatiotemporal patterns of seismic activity and identify key factors affecting impact hazard. It has been established that the greatest number of dynamic manifestations is associated with the intersection of large tectonic faults, such as the Rudny fault, with zones of discontinuous faults, as well as with the accumulation of compressive stresses near ore bodies. The stress-strain state of the Yuzhnoye deposit massif is complicated by the presence of abandoned pillars of off-balance ores, interstory pillars and outstanding depleted space, which creates conditions for the implementation of mining and tectonic impacts. Recommendations for further improvement of the monitoring and risk management system related to dynamic manifestations are proposed. The conclusions emphasize the need for an integrated approach, including instrumental monitoring, stress-strain modeling, and regular impact hazard analysis. These measures are aimed at improving the safety of mining operations and minimizing risks in fields characterized by high seismic activity.

Abstract Over the past decade, the development of shale gas in the southwestern Sichuan foreland thrust belt, China, has led to a significant increase in induced seismicity, including one of the world's largest hydraulic fracturing (HF)‐related induced earthquake (ML 5.4), occurring in the Weiyuan anticline. Here, we investigated the structural and mechanical evolution of the Weiyuan anticline and its relationship with HF‐induced earthquakes using seismic interpretation, the discrete‐element method (DEM), and three‐dimensional structural modeling. Interpretation of the seismic reflection profiles revealed a basement‐involved wedge structure and two west‐dipping multi‐bending thrust ramps in the basement. East of the Weiyuan anticline, extensive small‐displacement thrust faults developed between the Cambrian and Silurian shale detachments in the sedimentary cover. DEM simulation showed that the structural wedge formed by the underlying blind thrust ramp and back thrust (BT) controlled the Weiyuan anticline formation. With increased shortening, the fault slip continued to propagate east of the Weiyuan anticline along the Cambrian detachment, leading to the development of extensive thrust faults. 3‐D structural modeling showed that M > 4 induced earthquakes were primarily located on a BT in the structural wedge, while M < 4 events were distributed along the hydro‐fractured Silurian shale and Cambrian detachment. Densely developed thrust faults in the sedimentary cover connect the overpressured Silurian shale to the Cambrian detachment, promoting the downward diffusion of fluid pressure and favoring micro‐small M < 4 induced seismic events. This study provides new insights into the seismic hazard assessment of HF development in fold‐and‐thrust belts.

This study analyzes the temporal dynamics of instrumental seismicity recorded in the Pertusillo reservoir area (Southern Italy) between 2001 and 2018. The Gutenberg–Richter analysis of the frequency–magnitude distribution reveals that the seismic catalog is complete for events with magnitudes M≥1.1. The time-clustering of the sequence is at both global and local levels with a coefficient of variation Cv and Lv significantly beyond the 95% confidence band. The Allan Factor method, applied to the series of earthquake occurrence times, corroborates the found time-clustering, showing a bi-fractal behavior indicated by the co-existence of two scaling regimes with a cutoff time scale τc≈45 days and two different fractal exponents, α≈0.3 for time scales less than τc and α≈1.2 for larger ones. The application of the correlogram-based periodogram to both the monthly number of events and the monthly mean water level of the Pertusillo reservoir identifies the yearly cycle as the most significant in both variables. The connection between seismicity and the water level is also demonstrated by the value above 0.5 of the Average Edge Overlap (AEO), a topological metric derived from the Visibility Graph method applied to both the monthly variables. Furthermore, the variation in the AEO between the monthly mean water level and the monthly number of events, along with the time delay between them, indicates that the first leads the second by 1 month.

Reactivation of critically-stressed basement faults and related induced seismicity in the southeastern Sichuan basin

Abstract Understanding the dynamics of microearthquakes is a timely challenge with the potential to address current paradoxes in earthquake mechanics, and to better understand earthquake ruptures induced by fluid injection. We perform fully 3D dynamic rupture simulations caused by fluid injection on a target fault for Fault Activation and Earthquake Ruptures experiments generating Mw ≤ 1 earthquakes. We investigate the dynamics of rupture propagation with spatially variable stress drop caused by pore pressure changes and assuming different slip‐weakening constitutive parameters. We show that the spontaneous arrest of propagating ruptures is possible by assuming a high fault strength parameter S, that is, a high ratio between strength excess and dynamic stress drop. In faults with high S values (low rupturing potential), even minor variations in Dc (from 0.45 to 0.6 mm) have a substantial effect on the rupture propagation and the ultimate earthquake size. Modest spatial variations of dynamic stress drop determine the rupture mode, distinguishing self‐arresting from run‐away ruptures. Our results suggest that several characteristics inferred for accelerating dynamic ruptures differ from those observed during rupture deceleration of a self‐arresting earthquake. During deceleration, a decrease of peak slip velocity is associated with a nearly constant cohesive zone size. Moreover, the residual slip velocity value (asymptotic value for a crack‐like rupture) decreases to nearly zero. This means that an initially crack‐like rupture becomes a pulse‐like rupture during spontaneous arrest. These findings highlight the complex dynamics of small induced earthquakes, which differ from solutions obtained from conventional crack‐like models of earthquake rupture.

ABSTRACT Accurate seismic hazard assessment and fluid infiltration analysis near dam reservoirs require detailed crustal structure data. This study explores the interplay between subsurface structures and reservoir-induced seismicity at the Song Tranh 2 dam in Vietnam, focusing on implications for dam safety. Utilizing data from over 7000 induced microearthquakes recorded between August 2013 and June 2017, we selected over 3300 microearthquakes (M ≤ 3.6), and then by calculating dispersion curves (0.6–3.0 s periods), we applied surface-wave tomography to derive anisotropic and isotropic shear-wave velocity models between 0.5 and 2.5 km depth. The results reveal significant crustal heterogeneity, including velocity anomalies that suggest potential fluid infiltration pathways, pore pressure variations, and stress field modifications. Geological units (e.g., amphibolite and migmatite) play a key role in influencing seismic activity, with variations in seismic velocities reflecting differences in lithology and deformation intensity. With a few exceptions, the final tomography and anisotropy models align well with the mapped geologic units delineating four distinct reservoir sectors, each defined by unique seismicity patterns and fast anisotropic direction (local tectonic stresses). The findings emphasize the role of fault systems in shaping the stress regime and anisotropy, providing insights into mechanisms driving reservoir-triggered seismicity. Horizontal shear-wave slices reveal high velocities in sectors consisting of amphibolite and mafic granulite, whereas low velocities dominate sectors covered by migmatic and mafic granulite units where fracturing and water infiltration are likely contributing factors to the observed velocity reduction. Moreover, the analysis identifies regions with limited seismicity, likely indicative of less deformable subsurface structures, which may reduce seismic risks in certain areas. Discrepancies between anisotropic and isotropic radial anisotropy models (VSH and VSV discrepancies) and peak-to-peak differences in these models offer valuable insights into the subsurface structure around main and secondary fault junctions. Anisotropic cross-section profiles emphasize fault lines and tectonic influences, whereas isotropic profiles provide details on geological units. Around faults, anisotropic fast directions are inferred to be obscured by cracks or fluid infiltration, as seen in isotropic VSV and VSH models.

ABSTRACT In Bommer et al. (2024), we presented a critical review of the process through which the current logic tree for the maximum magnitude used in seismic hazard and risk calculations for induced earthquakes in Groningen was obtained. The article intended to initiate a discussion for which our premise is that the current maximum magnitude distribution may be excessively conservative, impacting both the quantitative risk assessment and the public and regulatory perception of risk. In his Comment, Vlek (2024b) misrepresents our article and makes inferences that have no basis in our article. He also puts forward numerous ideas, many of which have no connection to our article and others of which seem to reflect statements that we make, despite having recently published a discursive article on this very topic. There are several serious technical weaknesses in the comment, which we explain in this reply to minimize the confusion that the comment could create.

ABSTRACT In their “Estimating the maximum magnitude of induced earthquakes in the Groningen gas field, the Netherlands,” Bommer, van Elk, and Zoback (BvEZ) present good reasons to revise the 2022 expert-panel assessment of the maximum possible earthquake magnitude (Mmax) in the Groningen gas field, but their timing (August 2024) and authorship are remarkable. Here, it is argued that: (1) induced Mmax arises from a changing seismic source, (2) effective safety communication requires clarification of the practical meaning of “logic tree,” “expert weight,” and “possible” versus “expected,” (3) multivariate sensitivity analysis is needed to appreciate the implications of Mmax, for example, surface (vibratory) ground movements, (4) independent peer review may be useful but too much asked, and that (5) possible conservatism in Mmax assessment may be due to (costly) precautionary reasoning under uncertainty. The importance of balanced multiparty risk communication is emphasized. Concluding remarks are about institutional responsibilities for (apparently) insufficient Mmax assessment in 2022, the implications of BvEZ’s current re-evaluation for further building reinforcement and restoration policies for Groningen, and the desirability of reviving the expert assessment process on Mmax, to validate BvEZ’s main proposal that, for Groningen, 3.6≤Mmax≤4.1. After the field’s recent closure, ever observable Mmax will probably never exceed the historical earthquake magnitude of 3.6 near Huizinge in 2012.