A New Concept for the Earthquake Vulnerability Estimation and its Application to the Early Warning System

Abstract

It has been widely recognized that systematic and continuous monitoring of earthquakes is necessary for early warning. On the other hand, investigation of the durability of surface ground and structures should always have priority, when estimating the damage caused by destructive earthquakes. To estimate the vulnerability of both surface ground and structures, Naka-mura (1997) proposed an effective approach called the K-value method. In this method, the deformation characteristics are approximated based on the amplification and the natural frequency information determined from microtre-mor measurements. These K-values, together with the acceleration are then used to calculate the strain of the ground and structures. Naka-mura (1997) verified this approach for several real earthquake cases by comparing estimated and actual damage. It was proven that it is possible to effectively estimate actual damage by combining continuously monitored earthquake motion with investigated characteristics of ground and structures. This paper addresses the formulation of the K d value (K-value for the derailment of trains), proposing the new characteristic parameters PI (P-wave Index) and DI (Damage Intensity) proposing to help define the destructiveness of the earthquake and effectively realize the P-wave alarm system. During an earthquake, as soon as P-waves arrive, the DI function can be calculated in real time. This new characteristic DI-value (DI V ) has a clear physical meaning and agrees very well with the instrumental seismic intensity of the Japan Meteorological Agency (Ijma)- The relation between DI V and I JMA can be approximately given as I JMA = D1v-0.6. This enables one to estimate the instrumental seismic intensity from DI V . Using this approach, it has been proved that, as with K-values, PI- and DI v -values can be used for early warning studies. In addition, actual damage can be accurately estimated and effective response can be decided on quickly.