Seismic wave amplification due to topography and geology in Kobe during Hyogo-Ken Nanbu earthquake

Abstract

The Hyogo-ken Nanbu Earthquake, 17 January 1995 caused by inland active faults resulted in a disaster belt zone of JMA intensity VII in Kobe city. In this paper, addressing attention to the geological features, the authors conducted computer simulation in order to interpret the above consequence. The gradually increasing surface alluvium toward the coast and the deep Osaka Group soils bounded by abrupt dipping of the rock formation at the foot of Rokko range are focused. The results shows that the former is related to the localized amplification of the short period motions (05 - 1s) while the latter to the long period motions (1 - 2s) and that the seismic amplification in alluvium might be more concerned with the heavy damage.