REVIEW ON VARIOUS EMPIRICAL METHODS IN ESTIMATING OF THE EARTHQUAKE MAGNITUDES FROM THE FAULTS IN KOREA

In South Korea, 20 units are operating and 8 units are under construction at 4 nuclear power plant sites. The nuclear facilities require to withstand an affect of the earthquake that might occur during their lifetime. However, it is not easy to predict accurately the maximum potential of earthquake that may occur in their sites. Up to now because there have not been found the Quaternary faults in Korean Peninsula, the design earthquake for nuclear power plant has not been considered the specific fault as a seismic source .

Recently, several Quaternary faults have been found along the Ulsan fault, Yangsan fault and eastern coastline in the southeastern part of the Korean peninsula. Because some of these faults, which are close to nuclear power plants, might be considered as a capable fault, they have been a very delicate matter, which needs to be deal with carefully in assessing the geologic and seismic hazards for nuclear power plants. The nuclear regulations require that seismic sources be characterized as to their potential for generating earthquakes and causing surface deformation. However, because of the low rate of seismicity and insufficient relationship between instrumental macro-seismicity and fault, there has been considerable debate among geologists. So, it is not easy to define whether the faults are active or not by the deterministic approach for design earthquake.

In this study, we preliminary review the various empirical methods for the potential earthquakes from fault parameters such as fault displacement, slip rate, rupture length, and so on. And we also discuss the reasonable methods, including the probabilistic seismic hazards, in estimating of design earthquakes for Korea nuclear power plants.