InSAR analysis reveals insights into the Ms 6.2 earthquake rupture and tectonic dynamics of the northeast margin of the Qinghai‒Tibet plateau

On 18 December 2023, an Ms 6.2 earthquake occurred in Jishishan County, Linxia Prefecture, Gansu Province, China. As the strongest seismic event in the region since records began, it caused significant casualties and property damage while providing a valuable opportunity to investigate local seismogenic structures. In this study, the seismogenic structure and seismogenesis mechanism of earthquakes were explored through high-precision coseismic deformation analysis and fault modeling combined with regional tectonic background and aftershock distribution data. The results indicate that the earthquake was a typical shallow thrust event with a maximum slip of 0.7 m and a minor dextral strike-slip component. A small-scale dextral adjustment fault that developed at the intersection of Lajishan, the Yellow River, and Jishishan is presumably the primary controlling factor for the dextral component. This study revealed that the northeastern margin of the Qinghai‒Tibet Plateau achieves strain release through local block rotation, resulting in a unique plateau expansion mode. These findings are crucial for understanding the tectonic evolution at the frontal edge of the Himalayan collision zone and improving regional strong earthquake risk assessment.