InSAR Deformation Analysis of the Ms 6.8 Earthquake in Dingri Tibet Based on LT-1A/B Satellites

At 09:05 AM on January 7, 2025, an earthquake with a magnitude of 6.8 occurred in Dingri County, Xigaze City, Tibet Autonomous Region, China. To obtain information on the large-gradient surface deformation caused by this earthquake, observations were conducted using the L-band LT-1A/B satellites. Although long-wavelength SAR data offers unique advantages for monitoring deformation in areas with large-gradient deformation and dense vegetation cover, its signals are susceptible to interference from the atmospheric ionosphere, which can lead to deformation measurement errors of several tens of centimeters. Addressing the aforementioned issues, this paper takes the 6.8magnitude earthquake in Dingri County, Xigaze City, Tibet Autonomous Region, China, as the research object and studies the correction of ionospheric interference errors in LT-1A/B satellite interferometry based on the Range Spectral Split Interferometry (RSSI) method. It acquires co-seismic interferometric pairs from LT-1A/B satellites spanning from January 3, 2025, to January 7, 2025, in the earthquake-affected area and conducts an ionospheric error correction experiment. The aim is to expand the surface deformation measurement capabilities based on LT-1A/B satellites and improve the measurement accuracy of the co-seismic deformation field. The results indicate that the RSSI method can effectively estimate the ionospheric errors in DInSAR results. The corrected results successfully restore the interferometric fringes in the earthquake-affected area, with the mean deformation value decreasing from 58.4 cm before correction to -0.9 cm after correction, and the standard deviation reducing from $143 \mathrm{~cm} /$ a to 6.1 cm. The accuracy is significantly improved, and the deformation results become more stable after correction, aligning better with the surface deformation patterns caused by the earthquake.