A Comprehensive Re-examination of the Geiyo Earthquake Disaster, 1906

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In this study, damage to Hiroshima-Kure-Matsuyama region due to the Geiyo earthquake of June 2, 1906 was re-examined from multi-viewpoints of various research fields in a comprehensive manner, aiming at promotion of regional disaster prevention through the inter-disciplinary collaboration.Firstly, in order to collect materials on the Geiyo earthquake disaster, literature survey and questionnaire investigation were conducted. Some of collected items, including newspaper articles, reconnaissance reports, archives of various organizations, etc. have been compiled as appendices of the final report for further study.Sonar investigation was carried out around the epicentral region in Aki-nada sea area to identify sea-bed fault causing the Geiyo earthquake. No sea-bed fault could be found, which proved that tsunami was not induced by the earthquake. Fault-rupture simulation using FEM method and synthesis of small fault-rupture process was also performed. Seismic intensity at Hiroshima-Kure re … More gion was estimated as V to VI on the JMA scale.Much effort was devoted to the investigation of ground condition of the disaster-stricken area. Predominant period of ground in Hiroshima and Kure was determined by conducting both measure of microtremors and theoretical analysis employing multi-reflection theory. Liquefaction possibility in Matsuyama was analyzed and it was concluded that no liquefaction occurred, which coincided with the fact that no evidence of liquefaction was found. Furthermore, "vibro-corer" was invented for future use as an easy-to-operate device to sample soil piece of alluvium layr.Fundamental studies on earthquake damage prediction were carried out in terms of seismic hazard analysis and damage assessment of buildings. In order to identify most-concerned seismic region, seismic hazard of Hiroshima city was analyzed, which showed the seismic activity in Aki-and Iyo-nada area had substantial contribution to the seismic hazard in Hiroshima. Dynamic response analysis of wooden structures and damage rate estimation of reinforced concrete structure were performed with emphasis on the effect of soil amplification. Less