Abstract:We calculate the GNSS velocity field of Maduo and its surrounding areas in Qinghai during 1999-2016 and 2017-2020, and using continuous slip regression method obtain the surface expansion, principal strain and maximum shear strain rates in this area before the Maduo earthquake. We analyze their dynamic evolution characteristics. The results show that: 1)There is no obvious adjustment of tectonic movement in this area before the earthquake; 2)Before the earthquake, the surface expansion rate near the epicenter decreased, indicating that the accumulation of strain energy near the epicenter decreased; 3)Before the earthquake, the maximum shear strain rate and the principal strain rate near the epicenter increased, indicating that the stress adjustment phenomenon occurred near the epicenter and the shear effect is enhanced.
HAN Shuaishuai,TAN Kai,LU Xiaofei et al. Analysis of Strain Evolution Characteristics before the 2021 Maduo 7.4 Earthquake in Qinghai[J]. jgg, 2023, 43(6): 641-645.