[S-SS10] Strong Ground Motion and Earthquake Disaster

[SSS10-P12] Exploring Velocity Pulses Generation through 3D Ground Motion Modeling in the 2016 Meinong, Taiwan Earthquake

*Yung-Ching Yang¹, Ming-Che Hsieh¹ (1.National Central University,Taiwan)

Keywords:Meinong earthquake, Finite-difference method, Velocity pulse

Recent studies have shown that velocity pulse waveforms are commonly observed during earthquakes, particularly in areas where the fault rupture exhibits directivity, advancing toward a specific direction and underscoring the influence of rupture directivity on seismic wave propagation. Waveforms resembling pulses are recognized for inducing more significant ground shaking and severe damage to structures, marked by heightened amplitude and longer durations. For example, the 2016 Meinong earthquake in Taiwan is notably characterized by its unique velocity pulse waveforms, a feature extensively documented in various research. This phenomenon led to more severe casualties and structural collapses in Tainan compared to Kaohsiung. Lee et al. (2016) conducted a joint source inversion of the Meinong, Taiwan, earthquake to elucidate the coseismic slip distribution and pinpoint factors responsible for larger ground motions in southwestern Taiwan. In this study, we investigate the generation of the velocity pulse through numerical simulation of the Meinong earthquake, leveraging the finite-fault model established by Lee et al. (2016). We extract the kinematic source parameters of the finite-fault model from Lee et al. (2016) and introduce perturbations to investigate the impact of various parameters on the generation of pulse wave signals, including the size of asperities, rupture velocity, and the source time functions of subfaults. Subsequently, we simulate seismic wave propagation using the 3D finite-difference method (FDM), considering the impact of different 3D velocity models on wave propagation. We calculate the ground motion at the seismic bedrock and on the ground surface, then compare these synthetic ground motions with empirical data and recent-develop ground motion models (GMM). This comparative analysis assists in identifying the factors that contribute to the generation of velocity pulses, thereby improving the accuracy and reliability of simulations for use in earthquake engineering applications.