Monitoring the groundwater storage (GWS) changes is crucial to the rational utilization of groundwater and to ecological restoration in the Loess Plateau of China, which is one of the regions with the most extreme ecological environmental damage in the world. In this region, the mass loss caused by coal mining can reach the level of billions of tons per year. For this reason, in this work, in addition to Gravity Recovery and Climate Experiment (GRACE) satellite gravity data and hydrological models, coal mining data were also used to monitor GWS variation in the Loess Plateau during the period of 2005–2014. The GWS changes results from different GRACE solutions, that is, the spherical harmonics (SH) solutions, mascon solutions, and Slepian solutions (which are the Slepian localization of SH solutions), were compared with in situ GWS changes, obtained from 136 groundwater observation wells, and the aim was to acquire the most robust GWS changes. The results showed that the GWS changes from mascon solutions (mascon-GWS) match best with in situ GWS changes, showing the highest correlation coefficient, lowest root mean square error (RMSE) values and nearest annual trend. Therefore, the Mascon-GWS changes are used for the spatial-temporal analysis of GWS changes. Based on which, the groundwater depletion rate of the Loess Plateau was −0.65 ± 0.07 cm/year from 2005–2014, with a more severe consumption rate occurring in its eastern region, reaching about −1.5 cm/year, which is several times greater than those of the other regions. Furthermore, the precipitation and coal mining data were used for analyzing the causes of the groundwater depletion: the results showed that seasonal changes in groundwater storage are closely related to rainfall, but the groundwater consumption is mainly due to human activities; coal mining in particular plays a major role in the serious groundwater consumption in eastern region of the study area. Our results will help in groundwater resource management, ecological restoration, and policy planning for coal mining and economic development.

A nearly 70 yr hiatus of major seismic activity in the central eastern Bayan Har block (BKB) ended on 22 May 2021, when a multislip-peak sinistral strike-slip earthquake struck western Maduo County, Qinghai. This earthquake, which ruptured the nearly 170 km long Kunlun Pass–Jiangcuo fault, is a rather unique event and offers a rare opportunity to probe the mechanical properties of the intraplate lithosphere of the central eastern BKB. Here, we inferred the fault geometry associated with the Maduo earthquake using Interferometric Synthetic Aperture Radar (InSAR), and relocated aftershocks and inverted the slip distribution through InSAR radar phases and range offsets. Our analysis revealed that the geometry of the fault varies along the strike: the southeastern end of the fault dips steeply to the northeast, whereas the northwestern end dips southwestward. Using the combined datasets to constrain a coseismic slip, we found that the 2021 Maduo event was dominated by sinistral strike-slip movement, with a slight normal-slip component at a shallow depth, rupturing the steep-dipping fault for nearly 170 km in length. Five asperities were detected along the fault strike in the shallow crust (0–12 km) with a peak slip of ∼4.2 m corresponding mostly to simple structures, namely, continuous and straight rupture segments, suggesting that the rupture propagated across geometrical barriers in a multiasperity way. Based on an analysis of the strain field and the focal mechanisms of both the 2021 Maduo earthquake and historical earthquakes that have occurred in the BKB, we propose that the fault zones within the BKB can also generate large earthquakes and have the ability to accommodate the ongoing eastward and northeastward penetration of the Indian plate into the Eurasian plate.

The 28 September 2018 Mw 7.5 Palu earthquake occurred at a triple junction zone where the Philippine Sea, Australian, and Sunda plates are convergent. Here, we utilized Advanced Land Observing Satellite-2 (ALOS-2) interferometry synthetic aperture radar (InSAR) data together with broadband regional seismograms to investigate the source geometry and rupture kinematics of this earthquake. Results showed that the 2018 Palu earthquake ruptured a fault plane with a relatively steep dip angle of ~85°. The preferred rupture model demonstrated that the earthquake was a supershear event from early on, with an average rupture speed of 4.1 km/s, which is different from the common supershear events that typically show an initial subshear rupture. The rupture expanded rapidly (~4.1 km/s) from the hypocenter and propagated bilaterally towards the north and south along the strike direction during the first 8 s, and then to the south. Four visible asperities were ruptured during the slip pulse propagation, which resulted in four significant deformation lobes in the coseismic interferogram. The maximum slip of 6.5 m was observed to the south of the city of Palu, and the total seismic moment released within 40 s was 2.64 × 10²⁰ N·m, which was equivalent to Mw 7.55. Our results shed some light on the transtensional tectonism in Sulawesi, given that the 2018 Palu earthquake was dominated by left-lateral strike slip (slip maxima is 6.2 m) and that some significant normal faulting components (slip maxima is ~3 m) were resolved as well.

Many theoretical and experimental studies have been carried out in order to improve the efficiency and reduce labor for power line inspection, but problems related to stability, efficiency, and comprehensiveness still exist. This paper presents a multiple sensors platform method for overhead power line inspection based on the use of a large unmanned helicopter. Compared with the existing methods, multiple sensors can realize synchronized inspection on all power line components and surrounding objects within one sortie. Flight safety of unmanned helicopter, scheduling of sensors and exact tracking on power line components are very important aspects when using the proposed multiple sensors platform, therefore this paper introduces in detail the planning method for the flight path of the unmanned helicopter and tasks of the sensors before inspecting power lines, and the method used for tracking power lines and insulators automatically during the inspection process. To validate the method, experiments on a transmission line at Qingyuan in Guangdong Province were carried out, the results show that the proposed method is effective for power line inspection.

The Coulomb stress change has been widely employed to interpret mainshock‐mainshock and mainshock‐aftershock triggering as well as interactions amongst earthquake faults and volcanoes. This quantitative index is computed based on the Coulomb failure criterion and is a function of fault parameters including the source and receiver fault geometries, the friction coefficient on the receiver fault, and Skempton's coefficient of the host rock. Thus, for the robust determination of the Coulomb stress change, the sensitivity of the Coulomb stress change to these model parameters should be thoroughly assessed. However, notwithstanding numerous case studies, almost no systematic investigation of the sensitivity of the Coulomb stress change has been performed. Here we present an error estimator for the Coulomb stress change and then quantitatively investigate the sensitivity of the Coulomb stress change to the fault model parameters for the 2008 M_w 7.9 Wenchuan earthquake. Our results indicate that for this case the Coulomb stress change is the most sensitive to the uncertainty in the dip angle of the receiver fault, while the influences of the uncertainties in the slip model of the source fault, the strike, and rake angles of the receiver fault, and the friction and Skempton's coefficients cannot be neglected. Accordingly, it is crucial to perform a realistic estimate of the uncertainty in the Coulomb stress change. By performing such calculation, future Coulomb stress analyses such as the stress triggering of earthquake sequence and the likelihoods of potential earthquakes could be based on more robust Coulomb stress change maps.