지질도를 이용한 한반도 지반정보의 개략적 분류

Abstract

Studies of the earthquake ground motion consider the soil properties or the bed rock properties in the upper 30 m. The average shear wave velocity in the upper 30 m defined from borehole data is routinely used for classifying the site conditions. However, it is difficult to classify the site condition using the limited borehole data to cover the whole Korean Peninsula. In the study of Lee et al. (2001), site classification of Taiwan was refined using surface geology from the geologic map, geomorphologic data, and borehole data following the guidelines of National Earthquake Reduction Program (NEHRP). Wald and Allen (2007) defined shear wave velocity using slope of topography or gradient in global scale. They also compared their results in the Taiwan region to those proposed by Lee et al. (2001). In this study, we used geologic map, geomorphologic data, estimated average shear wave velocity from slope of topography, and borehole data to define the site conditions of the Korean Peninsula. We compared our results to the borehole data or seismic site condition data which include seismometer locations and ground conditions. There are some differences between our results and seismic site condition data. The discrepancy is attributed to the relatively large scale geologic map (1:250000) which may not include accurate site condition of the regions. Estimated site conditions of the study, however, agree with those from borehole data when a 1-mile buffering distance is applied to geologic condition boundaries. These results provide useful information for the further study of regional hazard estimation, risk management, and other seismological and geotechnical applications.