Three-dimensional ground motion simulations by the stochastic finite-fault method for the Yangbi, Yunnan Ms6. 4 earthquake on May 21, 2021

An M(s)6. 4 earthquake occurred in Yangbi county, Yunnan Province on May 21, 2021, and the epicentral area suffered from strong earthquake damage. The modified stochastic finitefault method was used to reproduce the three-component ground motions at 28 strong -motion stations triggered in the Yangbi n6. 4 earthquake using a series of source kinematic rupture models stochastically generated. Compared with the observed ground motions, the earthquake stress drop and the potential source rupture model were firstly estimated. Moreover, groundmotion acceleration time histories at 2823 virtual observation points produced by the Yangbi n6. 4 earthquake were provided by the stochastic finite-fault simulation. The peak ground accelerations (PGAs) and peak ground velocities (PGVs) of the simulated ground motions, in good agreement with the observed values, well describe the distance attenuation, the near-field saturation effects and the rupture directivity effects. Meanwhile, amplitude and shape of 5% -damped pseudo spectral accelerations (PSAs) also show good agreement between the simulated and observed ground motions. The simulations well represent the observations at a wide period range from 0. 05 to 10 s. The seismic intensity map was plotted based on the simulated three-component recordings, approximately consistent to that officially released by the Earthquake Administration of Yunnan Province. The epicentral meizoseismal area reached a highest intensity Ell. Intensity to the SE of epicenter is generally higher than that to the NW due to the source rupture directivity. High intensity anomalous areas occur along the west bank of Erhai Lake due to the local site condition.

Automated summary

The study used the modified stochastic finite-fault method to simulate the ground motions of a magnitude 6.4 earthquake in Yangbi county, Yunnan Province. The results demonstrated good agreement with observed values, provided estimates for earthquake stress drop and rupture models, and analyzed pseudo spectral accelerations (PSAs) and seismic intensity maps.