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Fault fracture zone evaluation using borehole geophysical logs; case study at Nojima fault, Awaji island; Kosei butsuri kenso ni yoru danso hasaitai no hyoka

Abstract

Ikeda, et al., in their examination of log data obtained from a borehole (2000m deep) drilled at Ashio, Tochigi Prefecture, where micro-earthquakes swarm at very shallow levels, pay special attention to porosity. Using correlationship between the porosity and elastic wave velocity/resistivity, the authors endeavor to find the presence of secondary pores, dimensions of faults, composition of water in strata in faults, and difference in matrix between rocks, all these for the classification and evaluation of fault fracture zones. In the present report, log data from a borehole (1800m deep) drilled to penetrate the Nojima fault (Nojima-Hirabayashi, Awaji island) that emerged during the Great Hanshin-Himeji Earthquake are analyzed in the same way as the above-named Ashio data, and the results are compared with the Ashio results. Immediately below the Nojima-Hirabayashi fault fractured zone, stress is found remarkably reduced and the difference stress quite small in size. This is interpreted as indicating a state in which clay has already developed well in the fault fractured zone ready to allow the occurrence of shear fracture or a state in which such has already occurred for the release of stress. 4 refs., 5 figs.
Authors:
Ikeda, R; Omura, K; [1]  Yamamoto, T [2] 
  1. National Research Institute for Disaster Prevention, Tsukuba (Japan)
  2. Geophysical Surveying and Consulting Co. Ltd., Tokyo (Japan)
Publication Date:
Oct 22, 1997
Product Type:
Conference
Report Number:
ETDE/JP-98751022; CONF-9710214-
Reference Number:
SCA: 150301; PA: JP-97:0G4588; EDB-98:072606; SN: 98001944524
Resource Relation:
Conference: 97. SEGJ conference, Butsuri tansa gakkai dai 97 kai (1997 nendo shuki) gakujutsu koenkai, Sapporo (Japan), 22-24 Oct 1997; Other Information: PBD: 22 Oct 1997; Related Information: Is Part Of Proceeding of the 97th (Fall, Fiscal 1997) SEGJ Conference; PB: 371 p.; Butsuri tansa gakkai dai 97 kai (1997 nendo shuki) gakujutsu koenkai koen ronbunshu
Subject:
15 GEOTHERMAL ENERGY; WELL LOGGING; BOREHOLES; GEOLOGIC FAULTS; GEOLOGIC FRACTURES; SEISMIC WAVES; VELOCITY; POROSITY; MICROEARTHQUAKES; STRESSES; CLAYS; SHEAR PROPERTIES; STRESS RELAXATION
OSTI ID:
622762
Research Organizations:
Society of Exploration Geophysicists of Japan, Tokyo (Japan)
Country of Origin:
Japan
Language:
Japanese
Other Identifying Numbers:
Other: ON: DE98751022; TRN: JN97G4588
Availability:
Available from Society of Exploration Geophysicists of Japan, 2-18, Nakamagome 2-chome, Ota-ku, Tokyo, (Japan); OSTI as DE98751022
Submitting Site:
NEDO
Size:
pp. 341-346
Announcement Date:

Citation Formats

Ikeda, R, Omura, K, and Yamamoto, T. Fault fracture zone evaluation using borehole geophysical logs; case study at Nojima fault, Awaji island; Kosei butsuri kenso ni yoru danso hasaitai no hyoka. Japan: N. p., 1997. Web.
Ikeda, R, Omura, K, & Yamamoto, T. Fault fracture zone evaluation using borehole geophysical logs; case study at Nojima fault, Awaji island; Kosei butsuri kenso ni yoru danso hasaitai no hyoka. Japan.
Ikeda, R, Omura, K, and Yamamoto, T. 1997. "Fault fracture zone evaluation using borehole geophysical logs; case study at Nojima fault, Awaji island; Kosei butsuri kenso ni yoru danso hasaitai no hyoka." Japan.
@misc{etde_622762,
title = {Fault fracture zone evaluation using borehole geophysical logs; case study at Nojima fault, Awaji island; Kosei butsuri kenso ni yoru danso hasaitai no hyoka}
author = {Ikeda, R, Omura, K, and Yamamoto, T}
abstractNote = {Ikeda, et al., in their examination of log data obtained from a borehole (2000m deep) drilled at Ashio, Tochigi Prefecture, where micro-earthquakes swarm at very shallow levels, pay special attention to porosity. Using correlationship between the porosity and elastic wave velocity/resistivity, the authors endeavor to find the presence of secondary pores, dimensions of faults, composition of water in strata in faults, and difference in matrix between rocks, all these for the classification and evaluation of fault fracture zones. In the present report, log data from a borehole (1800m deep) drilled to penetrate the Nojima fault (Nojima-Hirabayashi, Awaji island) that emerged during the Great Hanshin-Himeji Earthquake are analyzed in the same way as the above-named Ashio data, and the results are compared with the Ashio results. Immediately below the Nojima-Hirabayashi fault fractured zone, stress is found remarkably reduced and the difference stress quite small in size. This is interpreted as indicating a state in which clay has already developed well in the fault fractured zone ready to allow the occurrence of shear fracture or a state in which such has already occurred for the release of stress. 4 refs., 5 figs.}
place = {Japan}
year = {1997}
month = {Oct}
}