Recent Advances in Developing Site-Specific Ground Motion Attenuation Relations for the Nuclear Power Plant Sites in Korea

Site-specific GM (ground-motion) attenuation relations for four Nuclear Power Plant sites in Korea were developed by regression analyses on the multiple simulations of PGA-values obtained by the RVT simulation method adopted in the stochastic GM method. Multiple simulations were made at distances of 1, 5, 10, 20, 50, 75, 100, 200, and 400 km. At each distance, four magnitudes were used: M 4.5, 5.5, 6.5, and 7.5. RVT simulation method was implemented by using the site-specific characteristics of site and path effect identified by analyzing the large spectral data set from small earthquakes and by using the regional source characteristics of a few moderate-to-large earthquakes occurring in and around the Korean Peninsula. In particular, the development of site-specific GM attenuation relations is possible by directly using the observed data from the seismic station located just right at the site of interest without considering the geotechnical properties of the foundation. These relations were compared with some observed data available up to now and the result of which showed good agreement each other supporting the validity of the relations. The result of this study is quite promising in that the characteristics of small earthquakes regarding the site and path effect can be used to predict strong ground-motion, although there still remains some issues that still have to be resolved such as of nonlinear behavior of the structural foundation and uncertainty of source scaling relations which are expected for large earthquakes. (authors)