Earthquake Interaction and Seismic Hazard Potentials in a Stable Intraplate Region: A Case Study for the Korean Peninsula

Session: Seismicity and Tectonics of Stable Continental Interiors [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

The Korean Peninsula is located in an intraplate region along the far eastern margin of the Eurasian plate. The 2011 Mw9.0 Tohoku-Oki megathrust earthquake caused distance-dependent coseismic and postseismic displacements. Medium weakening and stress perturbation occurred in the crust. The seismic velocities in the crust of the Korean Peninsula reduced by ~3 % instantly after the 2011 M9.0 Tohoku-Oki megathrust earthquake, recovering gradually with time. The occurrence rate of M5-level earthquakes increased by 4.7 times since the 2011 megathrust earthquake. The increased seismic risks continued until the medium properties and stress field are recovered. There is increasing concern regarding the possible occurrence of major events in regions with large populations. The identification of the seismicity properties and active faults is important for the proper seismic hazard mitigation. Historical seismic damage records suggest high seismic hazard potentials. The historical earthquakes with magnitudes of M5.5 to 6.8 occurred last 500 years around Seoul. We further investigate microearthquakes around Seoul metropolitan area. The hypocenters of earthquakes are refined to present the fault distribution. We calculate the cross correlation for 1176 inter-station pairs and obtain the Green’s functions of Rayleigh waves. The group velocity dispersion curves of fundamental-mode Rayleigh waves between 0.2 Hz and 5 Hz were measured using the multiple-filter technique. We obtain two-dimensional group velocity maps for discrete frequency bands using a fast marching method. We construct a 3D shear velocity model based on the 1D velocity structures for grid cells. The 3D velocity model is correlated with known geological features and surface topography.

Presenting Author: Tae-Kyung Hong

Authors