Geomorphological Criteria for Evaluating Liquefaction Potential Considering the Level-2 Ground Motion in Japan

In response to a bitter experience in the 1995 Hyogo-ken Nambu (Kobe) earthquake, the level-2 ground motion, extraordinarily strong shaking motion that would be caused by an earthquake directly under the area such as the 1995 earthquake, has been considered in seismic design of various kind of structures in Japan, in addition to the level-l general ground motion. Geomorphological criteria in the manual for zonation on liquefaction hazard issued by Land Planning Agency, which have been used a qualitative estimate of liquefaction potential were demanded to keep up with the above-mentioned trend of the time. The purpose of this study is to develop geomorphological criteria for evaluating liquefaction potential for the level-2 ground motion as well as the level-l ground motion based on case histories in the past earthquakes. The newly developed criteria are applied to the 1948 Fukui earthquake that induced the level-2 destructive motion. A liquefaction potential map is drawn up for the Fukui Plain affected by the earthquake. The result of the assessment based on the criteria was consistent with the actual performance of the ground during the 1948 event