Shear Wave Velocity Estimation in Korea Using P-Wave Seismograms

Abstract

The average shear wave velocity for a soil depth of 30 m (V-S30) is crucial for seismic hazard assessments. However,V(S30)measurements are not available at most recording stations in Korea. TheP-wave seismogram method is an efficient way to estimateV(S30)because it only utilizesP-wave seismograms recorded on the ground surface without boring process.V(S30)measurements for 51 recording stations are acquired from previous literature, and downhole tests were performed at 10 stations for additionalV(S30)measurements. TheP-wave seismogram method is validated for 50 stations using 359 seismograms recorded during 66 earthquake events with local magnitudes greater than 3.0. The average shear wave velocity for a certain depth (V-SZ) can be estimated using the ratio of radial to vertical components in the initialP-wave velocity seismograms, which can be converted toV(S30)using an empirical relationship. The residuals between the measured and estimatedV(S30)are divided into the overall bias, between-site residuals, and within-site residuals. The standard deviation for between-site residuals is 0.37, which is comparable with the values of previous studies for other countries. After bias correction, 70% of measuredV(S30)and estimatedV(S30)are within +/- 50% of each other. This study estimatesV(S30)values for 118 stations whereV(S30)is not available.