Characteristics of Cross-Fault Deformation Anomalies before the 2022 Lushan MS6.1, Markang MS6.0 and Luding MS6.8 Earthquakes and Post-Earthquake Changes
Abstract This paper presents a comprehensive analysis of the anomalous fault activity and post-earthquake changes around the epicenter of three earthquakes, based on the cross-fault short baseline and short level data accumulated in Sichuan for many years, through the analysis of the original observation curves, the quantitative calculation of the near-field 3D activity of the fault and the regional prediction effectiveness index. The results show that there were more short-term anomalies across the fault before the three earthquakes of MS6.0 and above, and the main characteristics are significant sudden jumps and huge anomalies. The three moderate-to-strong earthquakes occurred in the interior of the Bayan Har block, the boundary fault zone and the eastern boundary of the adjacent Sichuan-Yunnan rhombic block, which are the result of the joint action of stress transfer, tectonic activity and block motion. Therefore, the spatial and temporal overlap of the sites where anomalies occur is high, and strict differentiation and stripping is not possible. In addition, we observe the pre-slip phenomenon before the Luding MS6.8 earthquake before the viscous slip destabilization. One month after the earthquake, cross-fault deformation began to show adjustment recovery changes.
MA Lingli,CHEN Pu,PENG Liyuan et al. Characteristics of Cross-Fault Deformation Anomalies before the 2022 Lushan MS6.1, Markang MS6.0 and Luding MS6.8 Earthquakes and Post-Earthquake Changes[J]. jgg, 2024, 44(1): 75-81.
MA Lingli,CHEN Pu,PENG Liyuan et al. Characteristics of Cross-Fault Deformation Anomalies before the 2022 Lushan MS6.1, Markang MS6.0 and Luding MS6.8 Earthquakes and Post-Earthquake Changes[J]. jgg, 2024, 44(1): 75-81.
