← Back to Sessions

Region-specific Spatial Correlation Models for Ground Motion Intensity Measures in South Korea

Description: 

Seismic intensity maps, which depict the spatial distribution of intensity measures (IMs), are crucial for evaluating seismic disaster impacts after earthquake events. The ShakeMap system, developed by the USGS, is widely used to generate the intensity maps by interpolating the IMs spatially using a semi-variogram model. However, the default semi-variogram model pre-set in the ShakeMap, developed based on data from high seismic regions, may not be appropriate for the Korean Peninsula, which is classified as a low-to-moderate seismic region. The ground property of the Korean Peninsula is also characterized by shallow soil layers that amplify site effects in high-frequency ranges. This study aims to develop spatial correlation models tailored to South Korea using local seismic records and the region-specific ground motion model (GMM). We conducted the following steps to achieve this: 1) collect seismic data from 33 local earthquake events with M_L ≥ 3.5, 2) calculate residuals between observed IMs and predictions from the region-specific GMM, and 3) construct semi-variogram models using weighted least-squares regression to improve the fit for short separation distances across IMs, including PGA, PGV, SA_0.2, and SA_1.0. Validation tests conducted on the 2017 M_L 5.4 Pohang earthquake scenario showed that the developed region-specific semi-variogram model reduced the mean squared error (MSE) of intensity predictions by approximately 3.5% compared to the default ShakeMap model. This result highlights that the developed models generate intensity maps more accurately reflecting the spatial variability of ground motion in South Korea.

Session: Accuracy and Variability of Physics-based Ground Motion Modeling [Poster]

Type: Poster

Date: 4/15/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Bongseok

Student Presenter: Yes

Invited Presentation: 

Poster Number: 88

Authors