Chapter 13 Bedrock structure around faults and its relation to earthquake disaster

摘要: Abstract The frequency-wavenumber and horizontal-to-vertical ratio spectral analyses of microseisms (long-period microtremors), the bandpass filtering Bouguer gravity anomalies, were conducted to elucidate subsurface structure around eastern end severely damaged belt-like zone in Kobe-Hanshin area which appeared during 1995 Hyogokennanbu (Kobe) earthquake. A close relationship was found between fault-related bedrock configuration thus obtained distribution earthquake damage: a narrow severe damage located 1.5–2 km apart from basin edge where depth changes abruptly by several hundreds thousand meters. atributed amplification ground motions due specific bedrock, that is, focusing seismic waves and/or interference incident S-waves surface-waves secondarily generated at edge. It is pointed out, as lesson learned Hyogoken-nanbu disaster, investigation 3-D an urgent issue for hazard mapping urban on sedimentary basin.