Reconnaissance report on geotechnical damage caused by 2018 Hokkaido Eastern Iburi earthquake with JMA seismic intensity 7

Abstract The 2018 Hokkaido Eastern Iburi earthquake with the JMA seismic intensity of 7 occurred at a central south part of Hokkaido, Japan at 3:08 a.m. on September 6, 2018. Considering the social importance of this historical earthquake-induced geo-disaster, the Japanese Geotechnical Society (JGS) organized a “JGS Survey Team for Geotechnical Disasters in Hokkaido, Japan Induced by the 2018 Hokkaido Eastern Iburi earthquake,” mainly comprised of experts from the industry and academia of the Hokkaido branch of JGS. The aim of the survey team was to investigate the phenomena and factors which contributed to disaster recovery and disaster prevention/mitigation from both short- and mid- to long-term perspectives, and to provide academic advice to related government organizations. Based on the results of the site investigations conducted by the JGS survey team (JGS, 2019), this report provides a summary of the geotechnical damage caused by 2018 Hokkaido Eastern Iburi earthquake by presenting the detail of strong seismic motion and a various types of geo-disasters which occurred due to the earthquake. Furthermore, this report highlights future research issues on disaster prevention/mitigation in Hokkaido considering the features of the geo-disasters attributed to the earthquake.