Frictional and hydrologic properties of a major splay fault system, Nankai subduction zone

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

We report on laboratory experiments examining the frictional and hydrologic properties of fault gouge and wall rock along a borehole transect that crosses a major out-of-sequence thrust splay fault within the Nankai accretionary complex. At 25 MPa effective normal stress, the fault zone material is frictionally weak (μ ≤ 0.44) and exhibits low permeability after shearing (k < 5.5 × 10-20 m2). Fault zone samples are weaker and less permeable than the surrounding wall rocks, consistent with their slightly higher clay abundance. All samples exhibit velocity-strengthening frictional behavior over most of the experimental conditions we explored, consistent with aseismic slip at shallow depths. The fault and wall rock both exhibit prominent minima in the friction rate parameter (a - b) for sliding velocities of 1-10 μm/s (∼0.1-1.0 m/day), comparable to rates for slow slip events. This suggests that the frictional properties of fault zone material play a central role in governing the mode of slip on subduction megathrusts.

Original languageEnglish (US)
Article numberL20313
JournalGeophysical Research Letters
Volume36
Issue number20
DOIs
StatePublished - Oct 1 2009

Fingerprint

wall rock
subduction zone
fault zone
slip
rocks
fault gouge
thrust fault
boreholes
shearing
clays
sliding
permeability
friction
subduction
transect
borehole
clay
rate
material

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

@article{96f9cf0be53341f69e547617e34c69b0,
title = "Frictional and hydrologic properties of a major splay fault system, Nankai subduction zone",
abstract = "We report on laboratory experiments examining the frictional and hydrologic properties of fault gouge and wall rock along a borehole transect that crosses a major out-of-sequence thrust splay fault within the Nankai accretionary complex. At 25 MPa effective normal stress, the fault zone material is frictionally weak (μ ≤ 0.44) and exhibits low permeability after shearing (k < 5.5 × 10-20 m2). Fault zone samples are weaker and less permeable than the surrounding wall rocks, consistent with their slightly higher clay abundance. All samples exhibit velocity-strengthening frictional behavior over most of the experimental conditions we explored, consistent with aseismic slip at shallow depths. The fault and wall rock both exhibit prominent minima in the friction rate parameter (a - b) for sliding velocities of 1-10 μm/s (∼0.1-1.0 m/day), comparable to rates for slow slip events. This suggests that the frictional properties of fault zone material play a central role in governing the mode of slip on subduction megathrusts.",
author = "Ikari, {Matt J.} and Demian Saffer and Marone, {Chris J.}",
year = "2009",
month = "10",
day = "1",
doi = "10.1029/2009GL040009",
language = "English (US)",
volume = "36",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "American Geophysical Union",
number = "20",

}

Frictional and hydrologic properties of a major splay fault system, Nankai subduction zone. / Ikari, Matt J.; Saffer, Demian; Marone, Chris J.

In: Geophysical Research Letters, Vol. 36, No. 20, L20313, 01.10.2009.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Frictional and hydrologic properties of a major splay fault system, Nankai subduction zone

AU - Ikari, Matt J.

AU - Saffer, Demian

AU - Marone, Chris J.

PY - 2009/10/1

Y1 - 2009/10/1

N2 - We report on laboratory experiments examining the frictional and hydrologic properties of fault gouge and wall rock along a borehole transect that crosses a major out-of-sequence thrust splay fault within the Nankai accretionary complex. At 25 MPa effective normal stress, the fault zone material is frictionally weak (μ ≤ 0.44) and exhibits low permeability after shearing (k < 5.5 × 10-20 m2). Fault zone samples are weaker and less permeable than the surrounding wall rocks, consistent with their slightly higher clay abundance. All samples exhibit velocity-strengthening frictional behavior over most of the experimental conditions we explored, consistent with aseismic slip at shallow depths. The fault and wall rock both exhibit prominent minima in the friction rate parameter (a - b) for sliding velocities of 1-10 μm/s (∼0.1-1.0 m/day), comparable to rates for slow slip events. This suggests that the frictional properties of fault zone material play a central role in governing the mode of slip on subduction megathrusts.

AB - We report on laboratory experiments examining the frictional and hydrologic properties of fault gouge and wall rock along a borehole transect that crosses a major out-of-sequence thrust splay fault within the Nankai accretionary complex. At 25 MPa effective normal stress, the fault zone material is frictionally weak (μ ≤ 0.44) and exhibits low permeability after shearing (k < 5.5 × 10-20 m2). Fault zone samples are weaker and less permeable than the surrounding wall rocks, consistent with their slightly higher clay abundance. All samples exhibit velocity-strengthening frictional behavior over most of the experimental conditions we explored, consistent with aseismic slip at shallow depths. The fault and wall rock both exhibit prominent minima in the friction rate parameter (a - b) for sliding velocities of 1-10 μm/s (∼0.1-1.0 m/day), comparable to rates for slow slip events. This suggests that the frictional properties of fault zone material play a central role in governing the mode of slip on subduction megathrusts.

UR - http://www.scopus.com/inward/record.url?scp=72149106464&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=72149106464&partnerID=8YFLogxK

U2 - 10.1029/2009GL040009

DO - 10.1029/2009GL040009

M3 - Article

VL - 36

JO - Geophysical Research Letters

JF - Geophysical Research Letters

SN - 0094-8276

IS - 20

M1 - L20313

ER -