Kinematic deformation and intensity assessment of the 2021 Maduo MS7.4 earthquake in Qinghai revealed by high-frequency GNSS

Abstract

Rapid acquisition of the kinematic deformation field and seismic intensity distribution of large earthquakes is crucial for postseismic emergency rescue, disaster assessment, and future seismic risk research. The advancement of GNSS observation and data processing makes it play an important role in this field, especially the high-frequency GNSS. We used the differential positioning method to calculate the 1 HZ GNSS data from 98 sites within 1000 km of the MS7.4 Maduo earthquake epicenter. The kinematic deformation field and the distribution of the seismic intensity by using the peak ground velocity derived from displacement waveforms were obtained. The results show that: 1) Horizontal coseismic response deformation levels ranging from 25 mm to 301 mm can be observed within a 1000 km radius from the epicenter. Coseismic response deformation on the east and west sides shows bilateral asymmetry, which markedly differs from the symmetry presented by surface rupture. 2) The seismic intensity obtained through high-frequency GNSS and field investigations exhibits good consistency of the scope and orientation in the high seismic intensity area, although the former is generally slightly smaller than the latter. 3) There may exist obstacles on the eastern side of the seismogenic fault. The Maduo earthquake induced a certain tectonic stress loading effect on the western Kunlun Pass-Jiangcuo fault (KPJF) and Maqin-Maqu segment, resulting in higher seismic risk in the future.