Probabilistic Seismic Hazard Maps for Kanto Region : Modeling of Seismic Activity and Methodology for Probabilistic Seismic Hazard Analysis

The Headquarters for Earthquake Research Promotion of Japan published national seismic hazard maps for Japan in March 2005, at the initiation of the Earthquake Research Committee of Japan(ERCJ), on the basis of a long-term evaluation of seismic activity and a strong-motion evaluation. The National Research Institute for Earth Science and Disaster Prevention also promoted a special research project titled" National Seismic Hazard Mapping Project of Japan" to support the preparation of seismic hazard maps. Under the guidance of ERCJ, we carried out a study of hazard maps. There are two types of hazard map : one is a probabilistic seismic hazard map(PSHM), which shows the relation between seismic intensity value and its probability of exceedance within a certain time; the other is a scenario earthquake shaking map. In this paper, we focus on the PSHM for the Kanto region. We explain the modeling of seismic activity in the Kanto region and the methodology for the probabilistic seismic hazard analysis. Probabilistic seismic hazard maps for the Kanto region show the probability of ground motions equal to or larger than JMA seismic intensity 6- within 30 years. We separate contributions of various types of earthquake and make a PSHM for each. We can see that interplate and intraplate earthquakes without specified source faults make large contributions in the Kanto region.