Influence of far-field mega earthquake on cascade hydropower along the Yalongjiang river by simulating the 1850 Xichang M 7.5 earthquake

Researching and comprehending the characteristics of destructive seismic motions is essential for the seismic design of critical infrastructure. This study employs historical data from the M 7.5 earthquake that occurred in 1850 to simulate the impacts of a M 7.5 event on hydropower stations located in proximity to Xichang. Key factors taken into account in the simulation of seismic motion encompass uncertainties, mixed-source models, and the placement of asperities. Through these simulations, we acquired the peak ground acceleration (PGA), acceleration time histories, and acceleration response spectra for the hydropower facilities affected by the earthquake. To perform a comprehensive analysis, we utilized a multi-scenario stochastic finite fault simulation method to estimate parameters including the minimum, average, and maximum values of PGA and pseudo-spectral acceleration (PSA) response spectra. Additionally, we assessed the 50^th, 84^th, and 95^th percentiles values of the peak ground acceleration and pseudo-spectral acceleration response spectra. The simulation results also include peak ground acceleration field maps and peak ground velocity (PGV) field maps and intensity distribution maps pertaining to the earthquake. The findings demonstrate that the intensity maps produced through the stochastic finite fault method closely correspond with the intensity contour maps published of historical seismic records. These findings offer significant insights for the seismic safety evaluation and design of the specified hydropower stations. Moreover, this multi-scenario methodology can be effectively utilized for other critical infrastructure projects to derive dependable seismic motion parameters.