GIS-based regional assessment of seismic site effects considering the spatial uncertainty of site-specific geotechnical characteristics in coastal and inland urban areas

Earthquake-induced hazards are profoundly affected by site effects related to the amplification of ground motions, which are strongly influenced by site-specific geologic conditions such as soil thickness, bedrock depth and soil stiffness. Seismic disasters are often more severe in coastal or riverside locations than over stiff soils or rocks due to differences in local site effects. In this study, a recently developed geographic information system-based framework was applied in coastal and inland urban areas in Korea, and its applicability for regional assessments was evaluated using appropriate geostatistical zonation of site-specific seismic site effects. The proposed framework was composed of four functional components: multivariable statistical clustering, geostatistical optimization, geotechnical analysis, and local visualization. The framework was applied in the Seoul and Busan areas of Korea for consideration of site effects in inland and coastal urban areas. Such zones of thick soil, or with a deep depth to bedrock, are susceptible to ground motion amplification due to site effects during earthquakes. The earthquake losses associated with possible building damage can be estimated based on spatial zoning maps considering geological and topographical characteristics and by a comparison of the spatial correlations of seismic site classes between inland and coastal areas of Korea.