Widespread seismicity excitation throughout central Japan following the 2011 M=9.0 Tohoku earthquake and its interpretation by Coulomb stress transfer

Geophysical Research Letters
By: , and 

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Abstract

We report on a broad and unprecedented increase in seismicity rate following the M=9.0 Tohoku mainshock for M ≥ 2 earthquakes over inland Japan, parts of the Japan Sea and Izu islands, at distances of up to 425 km from the locus of high (≥15 m) seismic slip on the megathrust. Such an increase was not seen for the 2004 M=9.1 Sumatra or 2010 M=8.8 Chile earthquakes, but they lacked the seismic networks necessary to detect such small events. Here we explore the possibility that the rate changes are the product of static Coulomb stress transfer to small faults. We use the nodal planes of M ≥ 3.5 earthquakes as proxies for such small active faults, and find that of fifteen regions averaging ~80 by 80 km in size, 11 show a positive association between calculated stress changes and the observed seismicity rate change, 3 show a negative correlation, and for one the changes are too small to assess. This work demonstrates that seismicity can turn on in the nominal stress shadow of a mainshock as long as small geometrically diverse active faults exist there, which is likely quite common.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Widespread seismicity excitation throughout central Japan following the 2011 M=9.0 Tohoku earthquake and its interpretation by Coulomb stress transfer
Series title Geophysical Research Letters
DOI 10.1029/2011GL047834
Volume 38
Issue 15
Year Published 2011
Language English
Publisher American Geophysical Union
Publisher location Washington, D.C.
Contributing office(s) Earthquake Science Center
Description 5 p.; L00G03
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Geophysical Research Letters
Country Japan
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