Developing a seismic site classification map of Korea using geologic and topographic maps

Abstract

The aim of this study was to develop a proxy for the calculation of seismic wave site amplifications and response spectral shape, as a part of our work to implement a nationwide system of earthquake loss estimation for Korea. Although direct measurements are desirable for constructing a site-amplification map, such data are expensive and time consuming to collect. Thus we derived a site classification map of the southern Korean Peninsula using geologic and geomorphologic data, which are readily available for the entire area. Class B sites (mainly rock) are predominant in the study area, although localized areas of softer soils are found along major rivers and seashores. Independent T-g-based site classifications for 172 borehole sites have been petformed for comparison with the site classification map of the study. The excellent correspondence of our site classification and the T-g-based site classification, as high as 87%, confirmed that our map effectively represents the local behavior of site amplification during an earthquake. These results provide important information for improving loss estimation, not only due to earthquakes, but also due to flood, drought, landslide and other natural disasters.