Repeated Seismic Slipping Events Recorded in a Fault Gouge Zone: Evidence From the Nojima Fault Drill Holes, SW Japan

Abstract Drilling investigations and structural analysis of drill cores reveal that a fault gouge zone of 10–30 cm in width was observed at depths of ~260 to 900 m in nine drill holes that intersected the Nojima Fault (NF), on which the 1995 Mw 6.9 Kobe (Japan) earthquake occurred. Logging data and...

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Main Authors: Aiming Lin, Takafumi Nishiwaki
Format: Article
Language:English
Published: Wiley 2019-02-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2019GL081927
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author Aiming Lin
Takafumi Nishiwaki
author_facet Aiming Lin
Takafumi Nishiwaki
author_sort Aiming Lin
collection DOAJ
description Abstract Drilling investigations and structural analysis of drill cores reveal that a fault gouge zone of 10–30 cm in width was observed at depths of ~260 to 900 m in nine drill holes that intersected the Nojima Fault (NF), on which the 1995 Mw 6.9 Kobe (Japan) earthquake occurred. Logging data and an analysis of mesostructures and microstructures in drill cores show that (i) a ~60‐m wide fault damage zone containing a 10‐ to 30‐cm‐thick fault gouge zone developed in the NF, (ii) the fault gouge zone can be divided into 11–20 thin layers of different color, and (iii) the individually colored layers contain different color breccias of fault gouge that are offset and/or cut by cracks and crack‐filled calcite and quartz veinlets. Our results reveal that the fault gouge zone probably records more than 11–20 paleoseismic faulting events along the NF during the late Pleistocene‐Holocene.
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spelling doaj-art-669c70bbbb1a416daa83dfb80cecaa3a2025-08-20T03:09:45ZengWileyGeophysical Research Letters0094-82761944-80072019-02-014631276128310.1029/2019GL081927Repeated Seismic Slipping Events Recorded in a Fault Gouge Zone: Evidence From the Nojima Fault Drill Holes, SW JapanAiming Lin0Takafumi Nishiwaki1Department of Geophysics, Graduate School of Science Kyoto University Kyoto JapanDepartment of Geophysics, Graduate School of Science Kyoto University Kyoto JapanAbstract Drilling investigations and structural analysis of drill cores reveal that a fault gouge zone of 10–30 cm in width was observed at depths of ~260 to 900 m in nine drill holes that intersected the Nojima Fault (NF), on which the 1995 Mw 6.9 Kobe (Japan) earthquake occurred. Logging data and an analysis of mesostructures and microstructures in drill cores show that (i) a ~60‐m wide fault damage zone containing a 10‐ to 30‐cm‐thick fault gouge zone developed in the NF, (ii) the fault gouge zone can be divided into 11–20 thin layers of different color, and (iii) the individually colored layers contain different color breccias of fault gouge that are offset and/or cut by cracks and crack‐filled calcite and quartz veinlets. Our results reveal that the fault gouge zone probably records more than 11–20 paleoseismic faulting events along the NF during the late Pleistocene‐Holocene.https://doi.org/10.1029/2019GL081927fault gouge zonemesostructure and microstructureseismic slipNojima faultdrill coreearthquake fossil
spellingShingle Aiming Lin
Takafumi Nishiwaki
Repeated Seismic Slipping Events Recorded in a Fault Gouge Zone: Evidence From the Nojima Fault Drill Holes, SW Japan
Geophysical Research Letters
fault gouge zone
mesostructure and microstructure
seismic slip
Nojima fault
drill core
earthquake fossil
title Repeated Seismic Slipping Events Recorded in a Fault Gouge Zone: Evidence From the Nojima Fault Drill Holes, SW Japan
title_full Repeated Seismic Slipping Events Recorded in a Fault Gouge Zone: Evidence From the Nojima Fault Drill Holes, SW Japan
title_fullStr Repeated Seismic Slipping Events Recorded in a Fault Gouge Zone: Evidence From the Nojima Fault Drill Holes, SW Japan
title_full_unstemmed Repeated Seismic Slipping Events Recorded in a Fault Gouge Zone: Evidence From the Nojima Fault Drill Holes, SW Japan
title_short Repeated Seismic Slipping Events Recorded in a Fault Gouge Zone: Evidence From the Nojima Fault Drill Holes, SW Japan
title_sort repeated seismic slipping events recorded in a fault gouge zone evidence from the nojima fault drill holes sw japan
topic fault gouge zone
mesostructure and microstructure
seismic slip
Nojima fault
drill core
earthquake fossil
url https://doi.org/10.1029/2019GL081927
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AT takafuminishiwaki repeatedseismicslippingeventsrecordedinafaultgougezoneevidencefromthenojimafaultdrillholesswjapan