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Cohesional Slip on a Plate Subduction Boundary During a Large Earthquake
Author(s) -
Kameda Jun,
Hamada Yohei
Publication year - 2020
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 - 10.1029/2020gl088395
Subject(s) - slip (aerodynamics) , geology , trench , seismology , episodic tremor and slip , subduction , shear stress , shear (geology) , plate tectonics , fault (geology) , petrology , materials science , tectonics , composite material , physics , layer (electronics) , thermodynamics
The frontal part of the Japan Trench plate boundary fault, which slipped during the 2011 Tohoku‐Oki earthquake ( M w 9.0), is enriched in smectite and is intrinsically weak owing to the high swelling pressure of this mineral. Our rheometric experiments using analog fault materials demonstrate that “cohesional slip,” rather than frictional slip, is a realistic faulting process in the studied fault zone. The cohesional slip can be described by the Bingham plastic model. Consequently, the coseismic shear stress is described by the yield stress and plastic viscosity. Comparison of the results with the average shear stress derived from a previous study suggests that the slip zone thickness for cohesional slip is ~1.3 cm or less. This finding is consistent with textures characterized by discrete slip planes of comparable thickness observed in the recovered fault rocks, suggesting that these slip planes were activated during the Tohoku‐Oki earthquake.