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Numerical Simulation of Strong Ground Motion for the Mw 6.0 Jishishan Earthquake of 18 December 2023 in Gansu Province, China

Description: 

The Mw6.0 Jishishan earthquake on December 18, 2023 occurred along the eastern edge of the Tibetan Plateau and resulted in significant human casualties. To gain a better understanding of earthquake source properties and wave-propagation effects, we conducted simulations of the strong ground motion in the near field of the fault, incorporating 3D earth structure, finite-fault rupture, and realistic surface topography. In this study, the topography elevation from SRTM90, a global digital topography dataset is adopted. We utilized a 3D velocity model of the continental China lithosphere, USTClitho2.0, to simulate wave propagation in a box-like volume with a dimension of 300 km × 300 km at the surface and 30 km in depth. Our primary focus lies in the impact of the slip model on the simulated ground motions. The finite fault-slip models employed in this study include Zhang's preliminary rupture model obtained through iterative deconvolution and stacking of high-rate GPS and strong motion seismogram data, Zhang's rupture model obtained through joint inversion of teleseismic and strong motion data, Wang's rupture model and the GP source model. We apply a hybrid broadband method to simulate the ground motions within the frequency range 0.1–20 Hz. The low-frequency seismograms (<1hz) are simulated by 3D non-staggered grid finite-difference method, which incorporates boundary-conforming grids in the presence of an irregular free surface.The high-frequency seismograms are calculated using the stochastic approach. Then, we combine the high- and low-frequency seismograms to obtain broadband seismic motion by considering both amplitude and phase matching. We compare the simulated ground motions based on different finite fault models with the observed near-field records and the corresponding peak values. Furthermore, an analysis of the differences in strong ground motion calculated from different rupture models is presented. The results demonstrate the effectiveness of hybrid broadband method in predicting strong ground motion parameters, provided that appropriate Earth structure and earthquake rupture models are utilized.

Session: Numerical Modeling in Seismology: Developments and Applications - II

Type: Oral

Date: 5/1/2024

Presentation Time: 10:30 AM (local time)

Presenting Author: Nan

Student Presenter: No

Invited Presentation: 

Authors