The regional disaster investigation of Dadu River of Luding earthquake and feasibility study of Green's function database application

On September 5, 2022, an MS6.8 earthquake occurred in Luding County, Ganzi Prefecture, Sichuan Province, China, causing extensive damage. The scientific expedition team of the Institute of Geophysics of the China Earthquake Administration investigated the damage caused by the earthquake in several terrace hydropower stations on the main stream of the Dadu River and nearby areas. It was determined that the cascade power stations ware less affected by the earthquake and that normal operation was not affected. Using the empirical Green's function method and considering the uncertainty characteristics of the seismic source parameters, the ground motion acceleration time histories were estimated for a reasonable range of three typical locations in the seismic region: the Shimian Caluo area (termed location 1), the Xingkang Expressway bridge area in the Dadu River basin (termed location 2), and the area near the historical seismic ancient landslides (Mogangling, termed location 3). The preliminary results showed that: buildings at locations 1 and 3 may be destroyed by an earthquake of this strength, whereas the bridges in location 2 are less likely to be destroyed. Here, combining the results of the disaster investigation, the seismic network built by the key engineering project, and the results of the rapid estimation of the ground motion at typical locations, we consider the feasibility of applying the Green's function library based on the waveforms of actual small earthquakes in key project areas.