Damage Investigation of Surroundings of the Seismic Stations in the 2004 Niigataken-Chuetu Earthquake and Correspondence of Damage to Bulidings with Strong Ground Motions

Abstract

In the Niigataken-Chuetu earthquake occurred on October 23, 2004, the JMA seismic intensity scale 6 was recorded at many seismic stations. Especially at Kawaguchi, Kawaguchi-machi seismic station, JMA seismic intensity scale 7 was recorded for the first time since introduction of seismic intensity meters. Strong ground motion records with building damage data around the seismic stations make us possible to investigate correlation between damage to buildings and strong ground motion characteristics. We carried out damage investigation around the seismic stations where high JMA seismic intensity scale were recorded. We did not find heavily damaged buildings except for around the Kawaguchi-machi, JMA Ojiya and K-NET Ojiya seismic station in spite of high JMA seismic intensity scales and PGAs(peak ground accelerations). We investigated correlation between damage to buildings and strong ground motion characteristics using observed strong ground motion records. We found that the very short period, less than 0.5 sec., dominated many records whose JMA seismic intensity scales and PGAs are high but which did not bring about heavy damage to buildings. On the contrary, the 1-2 sec. period region dominated in the Kawaguchi-machi record which brought about heavy damage to buildings.