Coseismic Surface Horizontal Deformation of the 2022 Mw 6.6 Menyuan, Qinghai, China, Earthquake from Optical Pixel Correlation of GF-7 Stereo Satellite Images

Abstract

AbstractQuantifying surface deformation due to earthquake-related surface rupturing is a critical research focus. Localized offsets on the primary fault can be obtained via field measurements of dislocated landforms. However, effectively quantifying distributed deformation, which can extend for tens to hundreds of meters around the fault zone, has only become possible with the development of remote sensing technology and optical pixel correlation techniques. In this study, we correlated pre- and post-earthquake GaoFen (GF)-2 and -7 images that were ortho-rectified by a digital elevation model generated from GF-7 stereo images to obtain surface horizontal deformation of the 2022 Mw 6.6 Menyuan earthquake. The surface rupture had a total length of 28 km along two segments separated by a stepover; in this study, we focused on the northern segment (23.5 km), which was distributed along the Lenglongling fault (LLLF). The total surface offset measured by our study had the maximum value of 4.0 m and a mean value of 1.9 m. The mean offset measured by field observations captured just 50% of the mean offset from optical pixel correlation. Overall, 57% of off-fault deformation (OFD) occurred on the LLLF, which is a mature fault, owing to soft near-surface materials. Comparison of the surface offset measured by pixel correlation data in our study and near ground slip from joint inversion of Interferometric Synthetic Aperture Radar and pixel correlation data suggests that OFD played a significant role in accommodating the shallow slip. The results of this study offer new insight into the characteristics of surface deformation.