Abstract：We construct a three-dimensional viscoelastic finite element model of the eastern boundary fault zone of the Sichuan-Yunnan block. We calculate long-term average tectonic stress loading rate of the main faults with GNSS observation data as a constraint. According to the historical earthquake rupture models, we calculate the co- and post-seismic Coulomb stress changes in Xianshuihe fault zone, Longmenshan fault zone and so on. Then, we obtain the total stress evolution of the main fault zone in the study area. The results show that the tectonic stress loading rate on Xianshuihe fault zone, the southern section of Daliangshan fault zone, and Litang fault zone are high, which can reach 1.0 to 1.5 kPa/a. In addition, the tectonic stress accumulation in the 2022 Luding MS6.8 earthquake rupture area is about 0.177 MPa during the seismic recurrence cycle, and the historical events produced 0.07 MPa stress loading. The two stress accumulations together led to the Luding earthquake’s occurrence. In addition, the total stress accumulation on the Anninghe fault zone seismic gap area since the occurrence of the previous event(about 487 years ago) is about 0.3 MPa. The last rupture events occurred about 1 000 years ago in the southern section of Daliangshan fault zone and Litang fault zone, and the total stress accumulation in the seismic recurrence cycle is more than 1.0 MPa, which may indicate that these areas have greater seismic activity potential.
LI Yanxin,DONG Peiyu,ZHAO Bin. Stress Evolution Characteristics and Numerical Analysis of the Seismic Hazard of the Eastern Boundary Fault Zone of the Sichuan-Yunnan Block[J]. jgg, 2024, 44(4): 341-349.
