Source model for the Mw 6.0 earthquake in Jiashi, China on 19 January 2020 from Sentinel-1A InSAR data

Abstract

On January 19, 2020, an Mw 6.0 earthquake occurred in Jiashi, Xinjiang Uygur Autonomous Region of China. The epicenter was located at the basin-mountain boundary between the southern Tian Shan and the Tarim Basin. Interferometric Synthetic Aperture Radar (InSAR) is used to obtain the coseismic deformation field from both ascending and descending Sentinel-1A satellite images of the European Space Agency. The results showed that the coseismic deformation is distributed between the Kalping fault and the Ozgertaou fault. The earthquake produced significant deformation over an area of approximately 40 km by 30 km. The maximum and minimal displacements along the line of sight (LOS) are 5.3 cm and − 4.2 cm for the ascending interferogram and are 7.2 cm and − 3.0 cm for the descending interferogram, respectively. The fault geometry from the Multi peak Particle Swarm Optimization computation indicates that the seismogenic fault is a shallow low-dipping planar fault that is 4.58 km depth underground. The finite slip model inverted by the Steepest Descent Method implies that the rupture is dominated by a thrust fault. The slips are concentrated in a depth of 5–7 km with a maximum slip of 0.29 m. The estimated total seismic moment is 1.688 × 1018 Nm, corresponding to a magnitude of Mw 6.1. The seismogenic fault is the Kalping fault which has a listric structure. The coseismic deformation only occurred on the décollement layer and did not involve the ramp segment. The coseismic Coulomb stress changes have enhanced the stress on the deep margin of the Jiashi earthquake rupture area, indicating that there is still the possibility of strong earthquakes in this region in the future.

Strain Accommodation and Seismic Hazards of the Kalpin Fold‐And‐Thrust Belt, Southwestern Tian Shan Foreland, China: Insights From the 2020 Mw 6.0 Kalpin Earthquake

“…By constraining fault strike to east–west (260°–280°) and rake to nearly thrust (60°–130°), we obtained a focal mechanism in line with the regional tectonics and principal strain (dark gray focal mechanisms in Figure 5a). The optimal solution is a strike/dip/rake of 275°/22°/128° and a centroid depth of ∼8 km, this optimal mechanism is basically compatible with the previously published InSAR slip models (P. He, Wen, et al., 2021; S. Wang et al., 2022; Y. Yao et al., 2020; P. Yu et al., 2020), except a dip of 22° is a bit steeper than some of the InSAR models (e.g., S. Wang et al., 2022; P. Yu et al., 2020; Table S1 in Supporting Information S1). However, of those solutions with mechanisms consistent with the regional principal strain, the minimum misfit solution had the poorest P wave fits for stations to the north‐east (e.g., YAK; Figure 5d) despite having the lowest residuals overall.…”

“…The co‐seismic slip model agrees with those in previous studies, in which nonlinear inversion methods were applied to examine the fault geometry (e.g., Y. He, Wang, et al., 2021; P. Yu et al., 2020). In the post‐seismic period, afterslip was mainly distributed on the splay fault with a peak slip of 0.05 m; slight afterslip can be resolved on the décollement fault, where the co‐seismic rupture was located.…”

“…The relocated aftershocks were dominantly at depths of 7–22 km, below the rupture depth of InSAR‐derived models (Y. He, Wang, et al., 2021; Y. Yao et al., 2020; P. Yu et al., 2020). Our relocated aftershocks agree well with previous studies, which used different velocity structures with either homogenous or layered models (Y.…”

“…On 19 January 2020, a M w 6.0 earthquake occurred in the frontal margin of the KFTB (hereafter, the 2020 Kalpin earthquake; alternatively, 2020 Jiashi earthquake in some previous publications). This event has been studied by either combining Interferometric Synthetic Aperture Radar (InSAR) co‐seismic interferograms and geological data to model the slip distribution (P. He, Wen, et al., 2021; Y. Yao et al., 2020; P. Yu et al., 2020) or by integrating aftershock relocations to explore the relationship between the mainshock and aftershocks (Y. He, Wang, et al., 2021; Q. Yao et al., 2021; S. Wang et al., 2022).…”

Coseismic Deformation Field and Fault Slip Distribution Inversion of the 2020 Jiashi Ms 6.4 Earthquake: Considering the Atmospheric Effect with Sentinel-1 Data Interferometry

“…Since the tropospheric atmospheric delay will reduce the accuracy of the obtained seismic coseismic deformation field because of the strong topographic fluctuations in this area, it is necessary to take steps to mitigate the impact of atmospheric delay [ 4 ]. However, the majority of existing studies rely on Differential Interferometric Synthetic Aperture Radar (DInSAR) technology to directly obtain the seismic coseismic deformation field and frequently disregard the effect of the tropospheric delay phase on the final result [ 3 , 5 , 6 ]. In addition, the preliminary correction of the tropospheric delay phase in the Jiashi seismic zone revealed that the fitting residual of deformation data obtained by near-field regional simulation is approximately 2 cm [ 7 ].…”