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

Junpei Akamatsu, Keiichi Nishimura, Hitoshi Morikawa, Sumio Sawada, Kensuke Onoue, Hideo Saito, Mitsuru Jido, Takao Kagawa, Kazuo Kamura, Kenji Sato, Kunio Furuno, Masai Komazawa

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3 Citations (Scopus)

Abstract

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

Original languageEnglish
Pages (from-to)199-216
Number of pages18
JournalDevelopments in Geotechnical Engineering
Volume81
Issue numberC
DOIs
Publication statusPublished - 1997 Dec 1

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

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    Akamatsu, J., Nishimura, K., Morikawa, H., Sawada, S., Onoue, K., Saito, H., Jido, M., Kagawa, T., Kamura, K., Sato, K., Furuno, K., & Komazawa, M. (1997). Chapter 13 Bedrock structure around faults and its relation to earthquake disaster. Developments in Geotechnical Engineering, 81(C), 199-216. https://doi.org/10.1016/S0165-1250(97)80014-4