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Title: Depth dependence of the frictional behavior of montmorillonite fault gouge: Implications for seismicity along a décollement zone
Authors: Mizutani, Tomoyo
Hirauchi, Ichi, Ken
Lin, Weiren
Lin, Weiren
Sawai, Michiyo
Author's alias: 林, 為人
Keywords: décollement
friction
montmorillonite
seismicity
subduction zone
Issue Date: 16-Jun-2017
Publisher: American Geophysical Union (AGU)
Journal title: Geophysical Research Letters
Volume: 44
Issue: 11
Start page: 5383
End page: 5390
Abstract: To understand the seismogenic potential of shallow plate‐boundary thrust faults (décollements) in relatively warm subduction zones, water‐saturated Na‐montmorillonite gouges were sheared at a pore fluid pressure of 10 MPa, effective normal stresses (σneff) of 10–70 MPa, temperatures (T) of 25–150°C, and axial displacement rates of 0.03–3 μm/s. The Na‐montmorillonite gouges were frictionally very weak at all conditions tested (steady state friction coefficient μss = 0.05–0.09). At T ≤ 60°C, Na‐montmorillonite showed a transition from velocity‐strengthening to velocity‐weakening behavior with increasing σneff, whereas at T ≥ 90°C it was largely velocity neutral or velocity strengthening, irrespective of σneff. The rates of frictional healing (β) showed extremely low values (mostly <0.001) at all temperatures. Our results suggest that the existence of Na‐montmorillonite in the décollement zone at Costa Rica and Nankai promotes aseismic slip, particularly at shallow depths, forming weakly coupled regions.
Rights: An edited version of this paper was published by AGU. Copyright 2017 American Geophysical Union.
URI: http://hdl.handle.net/2433/254343
DOI(Published Version): 10.1002/2017GL073465
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