The Yangyuan Basin (YYB) is a fault basin located in the northern part of the Shanxi Graben System. Despite its relatively few historical earthquakes, the basin has exhibited active neotectonic deformation since the Cenozoic. This study utilizes Sentinel-1A/B SAR data from two tracks spanning 2017–2021, combined with GNSS velocity fields, to investigate the present-day crustal deformation characteristics, main faults activity parameters, and seismic hazards of the YYB through PS-InSAR technology and dislocation model. The results indicate that: (1) The dip-slip rates of the northern margin fault of the YYB gradually decrease from west to east, which may be attributed to the significantly higher uplift rate of the western segment of the Xiong’er Mountain fault block compared to its central and eastern segments under the regional tectonic stress field; in contrast, the dip-slip rates of individual segments of the north Liuleng Mountain fault are comparable. (2) The central and western segments of the northern margin fault of the YYB, as well as the Huajialing–Xiejiayao (HJL-XJY) segment and Huoshiling-Quchangcheng (HSL-QCC) segment of the north Liuleng Mountain fault, possess the potential to accumulate strain energy for moderate earthquakes. The estimated maximum moment magnitudes are approximately Ms 5.6–6.2 and Ms 5.8–6.0, respectively. (3) The YYB exhibits overall extensional tectonic characteristics; both the northern margin fault of the YYB and the north Liuleng Mountain fault exhibit dextral strike-slip movement. (4) The deformation of the YYB represents a superposition of tectonic and non-tectonic processes: under the regional tectonic stress field, the Xiong’er Mountain and Liuleng Mountain fault blocks undergo uplift, while the basin interior exhibits subsidence driven by the combined effects of tectonic loading and groundwater extraction.

The Tianshan orogen, located at the northern margin of the India-Eurasia collision zone, is one of the world's most seismically active intracontinental mountain belts. However, a comprehensive understanding of its crustal deformation, strain accumulation, and fault locking patterns remains limited due to the lack of large-scale, high-resolution geodetic observations. In this study, we integrate Sentinel-1 interferometric synthetic aperture radar (InSAR) time-series analysis with regional Global Navigation Satellite System (GNSS) data to reconstruct a three-dimensional (3D) deformation field covering the entire Tianshan range. We apply atmospheric corrections using ERA5 reanalysis and constrain the InSAR solutions with GNSS data to significantly improve their consistency, enabling reliable quantification of crustal motions. Our results reveal pronounced spatial variability in north-south shortening, with rates reaching similar to 20 mm/yr in the western segment (75 degrees-79 degrees E) and decreasing to 6-9 mm/yr in the eastern segment (85 degrees-87 degrees E). Uplift rates are higher in the South Tianshan (1.8-2.2 mm/yr) than in the North Tianshan (0.8-1.2 mm/yr), while strike-slip motions are concentrated along the southern foreland. Non-tectonic deformation is also identified, including large-scale subsidence due to groundwater extraction (similar to 34 mm/yr) and localized oilfield-induced subsidence (similar to 20 mm/yr). From the 3D deformation field, we derive the strain rate distribution and invert fault locking parameters using a block model with Bayesian optimization. High strain accumulation and strong locking are observed along the Pamir frontal thrust, the Maidan fault (which ruptured in the 2024 Mw 7.1 Wushi earthquake), the south Issyk-Kul fault, the Kepingtag fault (which ruptured in the 2020 Mw 6.0 Jiashi earthquake), and the Qiulitag belt. Our findings highlight the coupled tectonic and anthropogenic processes shaping Tianshan deformation and identify the western Qiulitag as a potential source for future large earthquakes.

Climatic and anthropogenic changes are reshaping global water resources, with the North China Plain (NCP) experiencing significant surface subsidence due to severe groundwater overexploitation over the past half-century. In this study, we integrate data from Interferometric Synthetic Aperture Radar, Global Navigation Satellite System, and hydraulic head measurements observed in 2015-2019 to investigate aquifers' physical properties and corresponding changes in groundwater storage in NCP. Geodetic measurements indicate seasonal and long-term deformation patterns. The amplitude of seasonal variation of deformation is up to 25 mm with phase lag behind the seasonal variation of water head. The integration of geodetic and hydrological data indicates that local aquifer storativity and clay lens thickness are 0.67x10-3-14.38x10-3 $0.67\times {10}<^>{-3}-14.38\times {10}<^>{-3}$ and 0.15-1.98 $0.15-1.98$ m, respectively. The average long-term subsidence due to sustained water storage loss is about 29 mm/yr, with a peak rate of similar to 120 mm/yr. Even though all regions show a long-term ongoing subsidence, the subsidence trend has slowed in about half of the NCP, which can be attributed to the impact of the South-to-North Water Diversion (SNWD) Project, especially in areas near the SNWD aqueducts. Moreover, we find a disparity in subsidence rates between Hebei and Shandong Provinces, reflecting the impact of different groundwater exploitation management in mitigating the subsidence. This research underscores the effectiveness of combining geodetic and hydrological data for assessing groundwater circulation and optimizing groundwater management.

The detection of seismic activity precursors as part of an alarm system will provide opportunities for minimization of the social and economic impact caused by earthquakes. It has long been envisaged, and a growing body of empirical evidence suggests that the Earth’s electromagnetic field could contain precursors to seismic events. The ability to capture and monitor electromagnetic field activity has increased in the past years as more sensors and methodologies emerge. Missions such as Swarm have enabled researchers to access near-continuous observations of electromagnetic activity at second intervals, allowing for more detailed studies on weather and earthquakes. In this paper, we present an approach designed to detect anomalies in electromagnetic field data from Swarm satellites. This works towards developing a continuous and effective monitoring system of seismic activities based on SWARM measurements. We develop an enhanced form of a probabilistic model based on the Martingale theories that allow for testing the null hypothesis to indicate abnormal changes in electromagnetic field activity. We evaluate this enhanced approach in two experiments. Firstly, we perform a quantitative comparison on well-understood and popular benchmark datasets alongside the conventional approach. We find that the enhanced version produces more accurate anomaly detection overall. Secondly, we use three case studies of seismic activity (namely, earthquakes in Mexico, Greece, and Croatia) to assess our approach and the results show that our method can detect anomalous phenomena in the electromagnetic data.

The southern margin of the South Tian Shan has drawn attention due to the intense compressional deformation and seismic activity associated with its thrust structures. However, the deformation and seismic activity in the thick-skinned thrust sheets of the root zones are minimal. The Mw 7.1 Wushi earthquake on 23 January 2024 serves as a window to reveal these unknown aspects of the seismic mechanisms in this structural setting. Using the Leveraging Interferometric Synthetic Aperture Radar (InSAR) technique, we unlock critical insights into the coseismic deformation fields. The seismogenic fault is an unmapped segment within the Maidan Fault system, exhibiting a strike ranging from 241° to 222°. It is characterized by a shallow dip angle of 62° and a deeper dip angle of 56°. Remarkably, the seismic rupture did not propagate to the Earth’s surface. The majority of slip distribution is concentrated within a range of 4 to 26 km along the strike, indicating that this earthquake was a thrust event on a blind fault within the thick-skinned tectonics of the South Tian Shan. Coulomb stress changes indicate that aftershocks primarily occur in the stress-loading region. Interestingly, some aftershocks are very shallow, causing clear surface deformation. Inversion results show that the fault planes of two aftershocks are located above the main shock fault plane at extremely shallow depths (<6 km). Combining geophysical profile data, we infer that ruptures in the deep-seated thick-skinned structures during the main shock triggered ruptures in the shallow thrust structures. This triggering relationship highlights the potential for combined ruptures of the main shocks and aftershocks in the deep-seated thick-skinned structures beneath the South Tian Shan to result in larger disasters than typical seismic events.

The north-south convergence and east-west extension of the Tibet Plateau are accommodated by a series of active strike-slip and normal faults, and normal-fault earthquakes are very active in the plateau. During 2020 to 2021, there were three normal-fault earthquakes, namely, the Dingri MS5.9 (2020-03-20), Biru MS6.1 (2021-03-19), and Shuanghu MS5.81 (2021-03-30) earthquakes. These three earthquakes were evenly distributed in the middle and southern parts of the plateau, which provides a favorable case for us to study the seismic deformation characteristics using interferometric synthetic aperture radar (InSAR) technology.We used InSAR technology and Sentinel-1 SAR image data to generate the coseismic deformation field of the three normal-fault earthquakes in the Tibetan Plateau. The results showed that the normal-fault earthquakes in the plateau were not pure normal-fault types, and the coseismic deformation field showed both subsidence deformation and strike-slip deformation. Based on the Okada elastic dislocation model and the coseismic deformation fields, we constrained and inverted the geometric parameters and the slip distribution of the fault plane to accurately determine the locations of the seismogenic faults. The seismogenic faults were mainly secondary concealed faults with dip angles < 60°, all of which were shallow earthquakes. The slip distribution was mainly concentrated within 12 km. Combined with geophysical recognition, we inferred that normal-fault earthquakes are widely distributed in the Qinghai-Tibet Plateau, and not limited to areas related to half-graben structure, and that the occurrence of normal-fault earthquakes largely depends on the gravitational potential energy in the extensional environment.

Moderate to strong earthquakes have been induced worldwide by shale gas development, however, it is still unclear what factors control their behaviors. Here we use local seismic networks to reliably determine the source attributes of dozens of M > 3 earthquakes and obtain a high-resolution shear-wave velocity model using ambient noise tomography. These earthquakes are found to occur close to the target shale formations in depth and along high seismic velocity boundaries. The magnitudes and co-seismic slip distributions of the 2018 Xingwen M(L)5.7 and 2019 Gongxian M(L)5.3 earthquakes are further determined jointly by seismic waveforms and InSAR data, and the co-seismic slips of these two earthquakes correlate with high seismic velocity zones along the fault planes. Thus, the distribution of high velocity zones near the target shale formations, together with the stress state modulated by hydraulic fracturing controls induced earthquake behaviors and is critical for understanding the seismic potentials of hydraulic fracturing.

基于2015—2019共4年的合成孔径雷达(SAR)卫星影像,提出一种广域合成孔径雷达干涉测量(In-SAR)时序分析技术,对华北平原的地表形变进行高精度连续监测.首先对SAR影像进行干涉处理,得到干涉图.在此基础上,使用经过并行化改进的永久散射体技术斯坦福改进(StaMPS)方法,提取干涉图中所有永久散射体(PS)像元,获取研究区域全分辨率的时序形变信息.之后,使用大气模型校正法与共景叠加法相结合的联合大气校正方法,估计并去除形变信息中的大气噪声.经过上述处理流程后,成功地获取华北平原地表大空间尺度、长时间跨度、全空间分辨率和高精度的形变信息,进而监测到平原内部由长期地下水开采导致的高达100 mm/a的大范围强烈沉降信号.相较于既有算法,并行化StaMPS方法通过在多个计算节点之间的实时分配,节约至少60％的计算时间,联合大气校正方法则可以去除约74.3％的大气噪声项,有效性显著高于两种校正方法的单独使用效果.广域InSAR时序分析技术可以有效地实现对大范围地表形变的高精度连续监测.

Groundwater overexploitation is a critical issue in the North China Plain (NCP), resulting in groundwater level decline and surface subsidence for the last half-century. This problem, however, has been greatly alleviated by the South-to-North Water Diversion (SNWD) Project since 2015. Monitoring of this process has been steadily improved in recent years using water level and geodetic observations. Here, we characterize the water storage change at the Huairou groundwater reserve site (HGRS) in Beijing due to the SNWD by combining Interferometric Synthetic Aperture Radar (InSAR) data of the Sentinel-1 satellites, continuous Global Positioning System (GPS) data, and well water level data observed during the same time. InSAR observations revealed subsidence up to ~400 mm in the Beijing plain but uplift at ~40 mm in the HGRS during 2015–2019, and more than 70% of the uplift occurred from October 2018 to January 2019. By integrating the most significant uplift deformation during October 2018 to January 2019 with water level observations at the same time, we estimated the storativity of the confined aquifer system at HGRS as 1.68–7.82×10−3, weighing in the correction for effective stress and surface deformation for various situations. Based on the estimated aquifer storativity and the observed water level change in the unconfined and confined aquifer, the recharged water storage for the confined and unconfined aquifers was estimated as 1.20–1.39×107 m3 and ~2.86×108 m3 from 6 October 2018 to 22 January 2019, respectively, which is about 4% and 91% of the surface water recharge through river channels in the same period due to the SNWD Project. Our study demonstrates that integration of geodetic and hydrological data can provide crucial information for the assessment of groundwater circulation and assistance of groundwater management.

Postseismic processes provide important opportunities to probe into and investigate the frictional, viscous, and porous properties of the seismogenic fault and the surrounding Earth media. To accommodate the temporal and spatial resolutions and long‐term baseline stability of different deformation data, we develop a full time‐series inversion (FTI) technique, which jointly inverts for afterslip patterns using full time series of Global Navigation Satellite System, SAR, and strainmeter data. The FTI linearizes the inversion problem with a prescribed source evolution function to achieve efficient inversion. We conduct synthetic tests to validate the spatial and temporal resolution of the FTI algorithm. FTI outperforms static inversion techniques in terms of inversion stability under high noise level. We apply different parameterization strategies to evaluate its resolution for slip evolution parameters. The tests show that FTI can discriminate spatially separated afterslip with distinct evolution functions. Finally, we apply FTI to investigate the afterslip process following the 2017 M w 7.3 Sarpol‐e Zahab earthquake that occurred along the Iran‐Iraq border in northwestern Zagros using Synthetic Aperture Radar Interferometry time series derived from the Sentinel‐1 observations 1 year after the mainshock. Similar to the synthetic tests, the algorithm is capable to discriminate afterslip with different evolution functions in the up‐ and downdip portions of the coseismic rupture zone. By comparing with the stress‐driven afterslip model simulated using rate‐strengthening frictional law, we demonstrate the stability of FTI in resolving the afterslip process. We emphasize the importance of incorporating early postseismic observations for deciphering afterslip evolution and frictional parameters.

随着国民经济建设的发展,高速铁路、风力和光伏发电站、大型输电网等遍布各个地区,在这些强电磁干扰环境下,能否获取或如何获取优质的大地电磁观测数据是亟待解决的问题.近2年来,我们在银川、运城、鹤壁和张家口4个测区开展了大地电磁测量,对约500个测点的数据采集和处理结果进行了分类总结,梳理出高速铁路、电气化铁路、风力发电站、光伏发电站、大型输电网等强电磁干扰环境下的45个典型测点.文中介绍了这45个测点谱数据的处理过程,展示了最终获取的视电阻率和阻抗相位曲线.结果说明,在强电磁干扰环境下采取加长观测时间的策略,使用优质的远参考数据对测区数据进行远参处理,采用非Robust法估计并仔细地选择谱数据,是在强电磁干扰环境下获取质量合格甚至优良的大地电磁数据的有效措施.

近年来随着我国页岩气大规模开采,四川盆地南部活动构造相对稳定的地区出现了一系列微震和有感地震,甚至是破坏性地震.这些地震是否为工业开采所诱发,目前已有研究从时空相关性给出了一些统计推断,本文则从形变观测角度分析页岩气开采能否产生可以检测到的地面形变,以揭示形变信息与页岩气开采的关系,尝试为页岩气开采提供有效的监测手段.基于长波ALOS-2卫星雷达数据对长宁页岩气区块近两三年内的InSAR地表形变展开探测,检测页岩气大规模生产可能造成的地面形变及其基本特征,同时使用Sentinel-1卫星雷达数据分析页岩气开发活跃时段内的形变时间序列信息.结果显示:考虑到不同观测技术的误差水平和观测角度差异,两种卫星数据均反映了一致的地表形变分布,且形变场与页岩气开采井的空间分布有很好的对应关系;压裂注液过程会造成地表快速隆升,生产过程中随着流体扩散地表会出现沉降和水平运动,初步揭示出页岩气生产过程中地面形变的非稳态变形特征.这表明在四川盆地南部复杂的形变观测条件下,InSAR技术是页岩气开采有效的监测手段,能够弥补地震学观测的不足.

Industrial production activities associated with salt mining, hydraulic fracturing, or geothermal exploitation can induce pore pressure and stress field changes, thus inducing seismic activity. Most of the events are not disastrous due to limited energy radiated. Here we report a Mw 5.8 damaging event that occurred in Changning, China on June 17, 2019, probably the largest induced event by industrial exploitation ever recorded. The earthquake is located within the Changning anticline, and it raises great concerns on why and how the event occurred in a relatively quiescent area in terms of tectonic activity. Moreover, it has been debated whether this earthquake ruptured solely on the fold-accommodation faults or also involved a deep-rooted fault under the anticline. By using InSAR data from two satellites, we investigate the detailed rupture and slip pattern of this earthquake. We propose a cascade rupture mode of the fold-accommodation faults, through poroelastic modeling of excess pore pressure by fluid injection and pumping operations and static Coulomb stress calculation on the pre-stressed faults. We argue that water injections may have triggered this event. The result highlights the importance of reassessing seismic hazard over similar tectonic environments with intensive industrial exploitation.

Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Geophysical Research Letters. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v1]Poroelastic stress triggered seismic activity in the Changning shale gas hydraulic fracturing region, Sichuan Basin, ChinaAuthorsWeiTaoRenqiLuiDDengfaHeJianbaoSunYuxinBaoYiduoLiuiDGuixiYiYanZhanWeikangZhangiDGuangshenLiuSee all authors Wei TaoState Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administrationview email addressThe email was not providedcopy email addressRenqi LuiDCorresponding Author• Submitting AuthorInstitute of Geology, China Earthquake Administration, Beijing 100029, China.iDhttps://orcid.org/0000-0001-7837-7965view email addressThe email was not providedcopy email addressDengfa HeSchool of Energy Resources, China University of Geosciences Beijingview email addressThe email was not providedcopy email addressJianbao SunState Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administrationview email addressThe email was not providedcopy email addressYuxin BaoState Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administrationview email addressThe email was not providedcopy email addressYiduo LiuiDUniversity of HoustoniDhttps://orcid.org/0000-0002-7978-8253view email addressThe email was not providedcopy email addressGuixi YiEarthquake Administration of Sichuan Provinceview email addressThe email was not providedcopy email addressYan ZhanState Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administrationview email addressThe email was not providedcopy email addressWeikang ZhangiDCollege of Energy Resources, China University of GeosciencesiDhttps://orcid.org/0000-0002-3305-1969view email addressThe email was not providedcopy email addressGuangshen LiuState Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administrationview email addressThe email was not providedcopy email address

On February 3rd, 2020, an isolated MS5.1 earthquake occurred in the northern section of the Longquanshan fault zone. This study aims at defining the geometry of seismogenic structures of this earthquake. In detail, centroid moment tensor inversion results show that the earthquake is characterized by a focal depth of 3.8 ​km with no corresponding surface faults. The strike/dip/rake angles for the two nodal planes are 205°/54°/96° and 15°/36°/82°, respectively. With the analyses of coseismic deformation of the surface obtained from InSAR measurements, together with the information of relocated hypocenters for a small number of aftershocks, it is concluded that a northwest-dipping nodal plane corresponds well to the source fault. The fault is suggested to have a length of about 2.8 ​km and a depth range of 2–5 ​km, and the centroid of the earthquake is located at 104.48°E and 30.71°N. Furthermore, multiple pieces of evidence indicate that this earthquake is partly driven by the overpressure effect associated with the adjacent natural gas packets, which is similar to several other moderate natural earthquakes in Sichuan Basin.

Cascade-up and/or slow-slip processes are commonly believed to control interactions between foreshocks, mainshocks and aftershocks, but their relative contributions remain poorly resolved. Discrimination between these processes will shed light on the understanding of earthquake physics, which requires exceptional observations of earthquake sequences. The well-recorded July 2019 Ridgecrest, California foreshock-mainshock-aftershock earthquake sequence provides such an opportunity. We perform simultaneous inversion of the July 4th M-W 6.4 foreshock and July 5th M-W 7.1 mainshock kinematic rupture models using SAR, strong motion, and GPS data. We also invert for afterslip models following the M-W 6.4 foreshock and the mainshock, respectively, by developing an inversion method that utilizes strainmeter, SAR and daily GPS time series. The inversion results show that the overall sequence involves no less than six fault segments, which include a main northwest-trending fault and secondary faults with sub-parallel and orthogonal geometry to the main fault. Co-seismic slip and afterslip have complementary patterns on the faults. During the early post-seismic period following the M-W 6.4 foreshock and the mainshock, moment release on the southwest-trending fault is dominated by aseismic slip, in contrast to the predominantly seismic slip on the northwest-trending fault. The mainshock appears to be triggered by a cascade migration of foreshocks on a northwest-trending fault. Slip on the southwest-trending fault migrates from the fault junction at the northeast end (following the M-W 6.4 foreshock) to the southwest end (following the mainshock) during the afterslip interval. The dual-mode (seismic versus aseismic) slip phenomena appear to be driven by co-seismic stress changes produced by the major events. (C) 2021 Elsevier B.V. All rights reserved.

The global and systematic coverage of Sentinel-1 radar images allows characterizing, by radar interferometry (InSAR), surface deformation on a continental scale. Our study focuses on the eastern part of the Tibetan plateau, where a combination of major strike-slip and thrust fault systems accommodates part of the deformation related to the collision between the Indian and Eurasian plates. We use an automated Sentinel-1 InSAR processing chain based on the NSBAS approach (Doin et al., 2011, Grandin, 2015) to measure the interseismic deformation across these fault systems. Processing is made on the CNES high-performance computer center in Toulouse in the FLATSIM project framework (ForM@Ter LArge-scale multi-Temporal Sentinel-1 Interferometric Measurement, Durand et al., 2019). We perform a time series analysis of the 2014-2020 Sentinel-1 InSAR data set, for 1200 km-long tracks (acquired along 7 ascending and 7 descending orbits), covering a 1 700 000 km2 area, with a 160 m spatial resolution. From about 130 acquisitions per track, we perform about 600 interferograms, with short, three months, and one-year temporal baselines. After inversion, we obtain time series of line-of-sight (LOS) delay maps, including residual atmospheric delay and network misclosure measurements. The time series are fitted by a seasonal signal plus a velocity trend. The velocity field on overlap areas agrees within less than 1~mm/yr. Finally, we decompose the LOS velocity maps into a vertical and a horizontal contribution. InSAR velocity maps highlight surface deformation patterns mostly localized on known major faults, short-wavelength patterns attributed to slope instabilities phenomena, and hydrological signals. The seasonal signal combines residual atmospheric phase delays and widespread hydrological phenomena in sedimentary basins, which we interpret in parallel with the regional geological map. Masking areas affected by dominant gravitational slope or hydrological deformation allows to better focus on tectonic deformation. We finally discuss slip partitioning on the various fault systems from the velocity maps and 2D profiles’ analysis.

We present a three-dimensional electrical resistivity model of the crust and upper mantle beneath the easternmost Kunlun fault (EKLf), obtained by three-dimensional inversion of magnetotelluric (MT) data. The crust of the Songpan-Ganzi block is characterized by high resistivity from the surface to a depth of around 20 km, and by low resistivity in the mid-lower crust in the depth range 20-40 km. The eastern edge of the high conductivity layer is coincident with the EKLf and the Huya fault. The electrical resistivity structure provides new insights into both (1) the generation of recent M > 6 earthquakes and (2) strain partitioning on this segment of the EKLf. Our model reveals that the Huya fault is the main branch of the EKLf in the region. Together with the EKLf, the Huya fault defines the boundary between the Songpan-Ganzi and Bikou blocks. The mid-lower crust of the Songpan-Ganzi block in this region has a low resistivity that likely represents a mechanically weak layer. The 2017 Jiuzhaigou Ms7.0 earthquake and other recent M > 6 earthquakes may have been controlled by the change in viscosity in the mid-lower crust that occurs across this boundary. The high conductivity may be acting as either (1) a channel of lower crustal flow, or (2) as a weak layer that decouples the upper and lower crust. The fact that the high conductivity layer does not extend along the north side of the Sichuan Basin questions the idea that crustal flow occurs in this area.