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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 |
Appears in Collections: | Journal Articles |
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