Author(s)

K. Wakamatsu & M. Matsuoka

Abstract

In a seismic hazard assessment, local geologic and ground conditions play important roles in characterizing and estimating hazards. The authors created a systematically standardized GIS-based ground-condition map containing the attributes of geomorphologic classification in grid cells of 7.5 arc-seconds latitude × 11.25 arc-seconds longitude for all of Japan. This paper introduces the concept of developing the 7.5-arc-second JEGM, and presents sample images of the JEGM. As an example of the database’s application to estimating the hazards—the average shear velocity of the ground in the upper 30 m–Vs30 is estimated and mapped for all of Japan. As the other examples of the database’s application being released by public agencies, presents prefectural seismic risk analyses, Seismic Hazard Maps for Japan, Quick Estimation System for Earthquake Maps triggered by observation records (QuiQuake) are presented. Keywords: GIS database, geomorphologic land classification, seismic hazard mapping, Vs30, seismic risk analyses. 1 Introduction A number of ocean-trench earthquakes including the Tokai, Tonankai and Nankai earthquakes and inland earthquakes hit the Tokyo metropolitan area are expected to occur with high probabilities in the near future in Japan. Local ground conditions play important roles in characterizing and assessing their hazards. However, neither a digital database nor paper maps of ground conditions throughout Japan had been available in a unified form.

Keywords

GIS database, geomorphologic land classification, seismic hazard mapping, Vs30, seismic risk analyses