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Evidence for slow slip following a moderate‐size earthquake ( M w =5.7) in a subducting plate
Author(s) -
Takai Kaori,
Kumagai Hiroyuki,
Fujii Naoyuki
Publication year - 1999
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 - 10.1029/1999gl900465
Subject(s) - slip (aerodynamics) , seismology , geology , episodic tremor and slip , geodesy , seismic moment , logarithm , san andreas fault , subduction , fault (geology) , tectonics , physics , mathematical analysis , mathematics , thermodynamics
Postseismic deformation following the Aichiken‐Tobu earthquake ( M w =5.7), which occurred on March 16, 1997 in central Japan, was detected by strainmeter networks. We show that this deformation can be consistently explained by slow slip on the fault, total amount of which is comparable to the high‐speed (coseismic) slip. The time constant of the slow after‐slip fitted to a logarithmic function is estimated to be roughly 0.25 hour. Comparison of this feature with that of Sanriku‐Haruka‐Oki earthquake ( M w =7.6), in which significant slow slip was detected by a GPS network, suggests a direct proportionality of the time constant and seismic moment of coseismic slip. We could detect very small signals (strain between 10 −7 and 10 −8 ) associated with this moderate‐size earthquake due to the high sensitivity of strainmeters. Strainmeters are especially useful in detecting afterslip from smaller earthquakes.