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Frictional properties of fault zone gouges from the J‐FAST drilling project ( M w 9.0 2011 Tohoku‐Oki earthquake)
Author(s) -
Remitti F.,
Smith S. A. F.,
Mittempergher S.,
Gualtieri A. F.,
Di Toro G.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl063507
Subject(s) - geology , trench , slip (aerodynamics) , drilling , fault gouge , seismology , comminution , plate tectonics , fault (geology) , san andreas fault , mineralogy , tectonics , composite material , materials science , metallurgy , physics , layer (electronics) , thermodynamics
Abstract Smectite‐rich fault gouges recovered during Integrated Ocean Drilling Program Expedition 343 (Japan Trench Fast Drilling Project (J‐FAST)) from the plate boundary slip zone of the 2011 M w 9.0 Tohoku‐Oki earthquake were deformed at slip velocities of 10 µm s −1 to 3.5 m s −1 and normal stresses up to 12 MPa. Water‐dampened gouges (1) are weaker (apparent friction coefficient, μ * <0.1) than room‐humidity gouges (apparent friction coefficient, μ * ~0.1–0.35) at all slip velocities, (2) are velocity insensitive to velocity weakening at all slip velocities, unlike room‐humidity gouges that are velocity strengthening at intermediate velocities ( V = 0.001–0.1 m s −1 ), and (3) have negligible peak μ * at high slip velocities ( V > 0.1 m s −1 ). A significant amount of amorphous material formed in room‐humidity experiments at low‐ and high‐slip velocities, likely by comminution and disordering of smectite. Our results indicate that the frictional properties of water‐dampened gouges could have facilitated propagation of the Tohoku‐oki rupture to the trench and large coseismic slip at shallow depths.