Three-dimensional Seismic Wave Propagation Simulations in the southern Korean Peninsula using Pseudo-dynamic Rupture Models
Abstract
Studies of historical earthquake records in the southern Korean peninsula have suggested possibilities of large (MW > 6) earthquakes at the region, yet the lack of instrumental data poses difficulties in accurately estimating the potential ground motions. Accurate ground motion simulation methods that can complement the observations are necessary, especially in the long periods (< 1Hz), to assess the impact of damaging earthquakes on the populated urban areas in proximity. In this study, we present a physically rigorous framework of ground motion predictions in the southern Korean Peninsula, based on three-dimensional (3-D) wave propagation simulations of potential earthquake scenarios implemented as ensembles of pseudo-dynamic rupture models. The pseudo-dynamic rupture models reproduce realistic earthquake scenarios consistent with the physical rupture process by emulating the correlation structures derived from a set of dynamic rupture models. The ensembles of earthquake source models were convolved with the pre-calculated 3-D Greens functions to synthesize full 3-component waveforms accounting for the finite-fault effects and the wave-propagation effects, up to 1 Hz. The simulations of MW 5.4 earthquake scenarios demonstrated the distributions of calculated peak ground motions to be consistent with the observations of the 2016 MW 5.4 Gyeongju earthquake. Features of rupture directivity, Love wave radiation patterns, and amplifications in the local basin structures were found in the spatial distributions of simulated peak ground motions. The simulation results indicated that the constructive interference of crustal shear wave phases associated with the post-critical reflections from the Moho discontinuity caused amplification of ground motions in the mid-western regions of the Korean Peninsula. Extensions of the simulations to earthquake scenarios of MW 6.0, 6.5, and 7.0 predicted Modified Mercalli Intensity scales ranging from I to V for most regions of the Korean Peninsula and maximum intensity of IX near the source. The application prospects of physics-based source and wave propagation simulations are promising, especially for ground motion predictions in regions of low current seismicity that have experienced large earthquakes historically.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.S11A..04L