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Abstract:
Korea is in a stable continental region (SCR), where large earthquakes do not occur frequently. However, Korea has suffered from infrequent yet damaging earthquakes in the past. Among the instrumented earthquakes, the largest was the 2016 M5.5 Gyeongju earthquake. The 2017 M5.4 Pohang earthquake was the second largest; but it was the most damaging one, due to its proximity to urban areas, shallow hypocentral depth of 5km, and the amplification of ground motions due to the dynamic response of the Pohang basin. Being in an SCR with a short history of instrumentation, South Korea has not collected sufficient instrumental data for data-driven ground motion models. To address this limitation, we implemented the hybrid ground motion simulation method of Graves and Pitarka (2010, 2015) to simulate earthquakes in South Korea, accounting for the crustal velocity structure and seismological characteristics of the Korean peninsula. We implemented a three-dimensional velocity model by Kim et al. (2017) and a one-dimensional velocity model by Kim et al. (2011). To model the earthquake source, we implemented Graves and Pitarka’s rupture generator with a magnitude-area scaling relationship developed for SCR by Leonard (2014).Using the implemented simulation platform, we simulated the 2016 M5.5 Gyeongju earthquake and the 2017 M5.4 Pohang earthquake and compared results with recorded ground accelerations at strong motion stations. Our study demonstrated the potential of physics-based ground motion simulation in South Korea, but it also suggested the need for further validation of the simulation method for earthquake engineering applications in South Korea.
