Estimation of Vs30 Using P-Wave Seismograms in South Korea

Session: Near-Surface Effects: Advances in Site Response Estimation and Its Applications [Poster]
Type: Poster
Date: 4/28/2020
Time: 08:00 AM
Room: Ballroom
Description: 

The time-averaged shear wave velocity for the top 30m soil deposits (V_S30) is widely considered as one of the most important factors affecting ground motion amplifications (e.g. Campbell and Bozorgnia, 2014). The shear wave velocity profile can be measured by various field tests. However, there are various restrictions to get the shear wave velocity profiles. Thus, some researchers have proposed correlations between V_S30 and readily available proxies such as surface geology, slope, terrain type, convexity and surface texture (e.g., Wills and Clahan, 2006; Wald and Allen, 2007; Allen and Wald, 2009; Wald et al., 2011; Kottke et al., 2012; Yong et al., 2012; Parker et al., 2017) which are associated with large uncertainties. Kim et al. (2016) verified, using P-wave seismogram in Central and Eastern North America (CENA) region, that the P-wave seismogram method yields more accurate V_S30 values than the other proxy methods.

In this study, we used 217 seismograms recorded on the ground surface at 37 seismic stations of Korea Meteorological Administration (KMA) during the 63 earthquakes events occurred in Korean Peninsular with magnitudes ranging from 3.0 to 5.0. We rotated two horizontal motions and estimated the motions in a radial direction. Then, we identified P-wave arrival times using the algorithm proposed by Kalkan (2016) and determined initial amplitudes of the radial and vertical motions. Using the ratio of radial and vertical component, we estimated V_SZ using the method proposed by Kim et al. (2016) and converted V_SZ to V_S30 based on the relationship by Kim et al. (2016). We compared the estimated V_S30 values with the V_S30 values measured by Lee et al. (2015). The method showed the trend with reasonable residual and accuracy. 65.73% (140/213) of measured V_S30 and estimated V_S30 are within ±100% of each other, and the standard deviation of total residuals is 0.57. When averaged by station, 70.27% (26/37) of measured V_S30 and estimated V_S30 are within ±100% of each other, and the standard deviation of between-site residuals is 0.46.

Presenting Author: Jaesung Kim

Authors