InSAR-based monitoring and analysis of Menyuan earthquake-induced surface deformations

Earthquake-induced surface deformations are characterized by large scales and extensive coverage, and the resultant secondary geological disasters significantly impact local infrastructure and engineering construction. Investigating the surface deformations caused by the Menyuan earthquake is critical for understanding the seismic deformation movement and identifying potential geological disasters. This study obtained the coseismic deformation field of the Menyuan earthquake using the differential interferometric synthetic aperture Radar (D-InSAR) technique. Based on the geometric relationships between the ascending descending passes, this study extracted the two-dimensional information of surface deformations induced by the Menyuan earthquake. The results show that the coseismic deformations occurred primarily at the intersection of Lenglongling and Tuolaishan faults. The line-of-sight (LOS) surface deformations from ascending and descending passes exhibited uplift of 0.40 m and 0.80 m and subsidence of -0.65 m and -0.70 m, respectively. As indicated by the analysis of two-dimensional deformation based on the ascending and descending LOS surface deformation results, the maximum amplitude of vertical deformations dominated by subsidence was -0.32 m and the maximum amplitude of horizontal deformation dominated by eastward motion was 0.87 m, suggesting significant horizontal seismic deformations and fault activity dominated by left-lateral strike-slip process. Based on the 21 scenes of Sentinel-1A SAR images covering the study area taken from the ascending pass, this study extracted the information on the surface deformations after the Mengyuan earthquake using the small baseline subset-interferometric synthetic aperture Radar (SBAS-InSAR) technique, determining the LOS time series and average deformation rates. The results show that from January 17, 2022 to September 26, 2022, the study area experienced relatively stable overall deformations and significant local deformations. The fault activity was identified as the primary factor affecting the surface deformations, with a maximum average deformation rate of 53 mm/a and a maximum deformation amplitude of 77 mm. The results of this study will provide technical support for earthquake disaster mitigation, emergency management, and sustainable socio-economic development.