Developing a 7.5-sec site-condition map for Japan based on geomorphologic classification

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.