Abstract Based on the GNSS velocity field from 2013 to 2018 in the Sichuan-Yunnan region, we calculate the regional strain rate fields, and analyze the current strain accumulation rates distribution of the eastern boundary of the Sichuan-Yunnan block. We then invert the degree of fault locking and slip-rate deficit on the eastern boundary of the Sichuan-Yunnan block, focusing on the analysis of the strain accumulation characteristics in the deep depth of the eastern boundary of the Sichuan-Yunnan block after the Lushan earthquake. Finally, combined with the results of historical earthquake rupture and fault Coulomb stress, we comprehensively analyze the risk of strong earthquakes in different segments of the eastern boundary of the Sichuan-Yunnan block. The results show that the eastern boundary of the Sichuan-Yunnan block presents obvious characteristics of left-lateral strain accumulation; the shear strain accumulation rate in the Sanchakou area is the largest, with a maximum value of 3.5×10-8/a. Moreover, the eastern boundary of the Sichuan-Yunnan block also exhibits NS-NE directed extension and EW-NW directed compression deformation. The Kangding-Shimian segment has the highest EW-NW compression strain rate of -3×10-8/a. The Anninghe-Zemuhe fault zone also exhibits E-W-directed compression; the E-W-directed compression strain rate is -2×10-8/a to -3×10-8/a, while the compression deformation of the Xiaojiang fault zone gradually slows down from north to south and turns into tensile deformation near the south of Dongchuan. The fault-coupling inversion results are consistent with the GPS strain rate results, and reflects the left-lateral shear strain and local compression or tensile strain accumulation characteristics of the eastern boundary of the Sichuan-Yunnan block. Comprehensive analysis shows that the Daofu-Bamei segment, the Moxi segment of the Xianshuihe fault zone, the Anninghe fault zone, and the Qiaojia-Dongchuan and Yiliang-Jianshui segments of the Xiaojiang fault zone currently have a high locking degree and a left-lateral slip rate deficit, resulting in high potential for the next strong earthquake.
LIU Xinzhong,ZHANG Fengshuang,MA Lingli et al. Current Strain Accumulation Characteristics and the Risk of Strong Earthquakes on the Eastern Boundary of the Sichuan-Yunnan Block[J]. jgg, 2022, 42(7): 687-693.
LIU Xinzhong,ZHANG Fengshuang,MA Lingli et al. Current Strain Accumulation Characteristics and the Risk of Strong Earthquakes on the Eastern Boundary of the Sichuan-Yunnan Block[J]. jgg, 2022, 42(7): 687-693.
