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Recovery of plate coupling at a ruptured asperity
Author(s) -
Yoshida Shingo,
Nakatani Masao,
Kato Naoyuki
Publication year - 2013
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/jgrb.50172
Subject(s) - slip (aerodynamics) , cutoff , asperity (geotechnical engineering) , coupling (piping) , limiting , geology , mechanics , physics , law , materials science , geotechnical engineering , thermodynamics , composite material , engineering , mechanical engineering , quantum mechanics , political science
Earlier earthquake cycle simulations using rate‐ and state‐dependent friction (RSF) law have revealed that frictional coupling at a ruptured asperity starts immediately after dynamic slip because of logarithmically time‐dependent healing. However, some Global Positioning System (GPS) inversion studies of the 2011 great Tohoku‐Oki earthquake suggest that afterslip continued for 7–8 months or longer in the deep seismogenic interface including asperities where M7 earthquakes repeatedly occurred. Nakatani and Scholz [[Nakatani, M., 2006]] introduced the intrinsic cutoff time t cx in the logarithmically time dependent healing and pointed out that a long t cx could lead to delayed start of frictional coupling. Assuming RSF laws into which t cx was incorporated, we conducted a numerical simulation using a block spring model. We defined the time required to restore frictional coupling as T cpl measured from the instant of dynamic slip. The value of T cpl for t cx = 10 −3 s was almost the same as T cpl in the conventional law, which was on the order of 10 min in the case of the aging law. It increased approximately in proportion to t cx for short t cx (≤1 s), whereas T cpl was not so sensitive to t cx for a long t cx (>1 s). Moreover, a long t cx cannot be reasonably assumed because the maximum slip velocity during dynamic slip decreased with increasing t cx , limiting the largest possible T cpl to be months at most. Friction laws with two state variables, each having a different cutoff time, were also investigated. The maximum slip velocity was determined by the smaller cutoff time, and T cpl was affected by the larger cutoff time. As a result, longer T cpl became possible, although the values are still on time scale of months.