History of Liquefaction Hazard Map Development and a New Method for Creating Hazard Maps for Low-Rise Houses

This paper introduces the development history, current situation and problems concerning hazard maps for soil liquefaction. A zonation manual produced by the TC 4 of ISSMFE in 1993, is introduced first. Then, the development of hazard maps for liquefaction in Japan is reviewed. A hazard map for liquefaction was first created by Ishihara and Ogawa in 1978. Currently, hazard maps exist for all administrative divisions of 47 administrative zones. However, they are not being fully used. In order to be fully used, hazard maps must be upgraded, mainly improving the following three points: i) accuracy and reliability, ii) maps specifically for low-rise housing, and iii) maps showing timelines of emergency risks immediately after an earthquake. In addition, there is a lack of risk communication between the government, home builders and residents. Therefore, in order to solve this problem, Japan’s Ministry of Land, Infrastructure, Transport and Tourism organized a technical committee to propose a method for creating liquefaction hazard maps, and published the “Liquefaction Hazard Map Guide for Risk Communication” in February 2021. It is expected that such risk communication will promote measures against liquefaction.