Composite Source Model for Broadband Ground-Motion Simulations: 2021 Mw 7.4 Maduo, China, Earthquake Case Study

Abstract

Abstract On 22 May 2021, at 2:40 a.m. (local time), an earthquake with a moment magnitude of 7.4 was reported to have occurred in Maduo County (34.59° N, 98.34° E), China. The focal depth was 17 km. After the earthquake, many scholars inverted the slip distribution of the Maduo earthquake based on ground-motion recordings, and the Global Positioning System and the Interferometric Synthetic Aperture Radar data. To verify the reliability of the fast estimation source model method adopted in this study, the hybrid slip model of the 2011 Mw 7.4 Maduo earthquake, in Qinghai Province, China, is synthetized based on the stochastic finite-fault model and the semiempirical relation between the earthquake magnitude (Mw) and source parameters. The truncated normal distribution and regional crustal structure are used to generate 30 sets of global source parameters, which describes that the deterministic characteristics of the source mainly include the size of the rupture fault, and the average slip, and the local source parameters. The local parameters include asperity and k2 model parameters. Finally, stochastic finite-fault modeling is adopted to synthetic the acceleration response spectra at four selected sites meeting different geological conditions and orientations, and the minimum residual principle is used to select the final slip model for the Maduo earthquake with the minimum residual of the average response spectra. The research results show that the width, maximum slip, and asperity body position of the source model estimated in this study are consistent with those of the inversion slip model, which verifies the reliability and applicability of this method. This work provides technical and theoretical support for rapid prediction of the source model of earthquakes with specific magnitudes.