P波初動を用いた震度予測方法の開発と緊急地震速報への応用

Abstract

The Japanese Meteorological Agency has started examination delivery of real time earthquake information since February 2005. Real time earthquake information gives the information of earthquake event before strong motion arriving. It is hoped that we can reduce the damage due to earthquake greatly by this. However, real time earthquake information has plural big problems. Precision of seismic intensity in particular is the first problem. Estimated seismic intensity by method that the Japanese Meteorological Agency recommends tends to become bigger than observed seismic intensity. It is thought that the reason is to calculate it from many experience equations in seismic intensity estimation. In addition, it is thought that experience equations used for estimation have regional characteristics to national average. Therefore, in this study, we suggest a method to estimate seismic intensity different from the method Japanese Meteorological Agency recommended. The new method estimate seismic intensity from initial part of P wave. In addition, we suggest seismic intensity estimation to the other site where P wave does not arrive at. The method calculates magnitude, epicentral distance with B-Δ method (Tukada et al 2004). We demand an attenuation relationship from calculated results. We perform seismic intensity predictions from a found expression to the other site. Initial up-and-down motion of P wave has a good relation with seismic intensity. The method developed in this study will be very useful for emergency system by using the Real-time earthquake information.