Imaging shear strength along subduction faults

Geophysical Research Letters
By: , and 

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Abstract

Subduction faults accumulate stress during long periods of time and release this stress suddenly, during earthquakes, when it reaches a threshold. This threshold, the shear strength, controls the occurrence and magnitude of earthquakes. We consider a 3-D model to derive an analytical expression for how the shear strength depends on the fault geometry, the convergence obliquity, frictional properties, and the stress field orientation. We then use estimates of these different parameters in Japan to infer the distribution of shear strength along a subduction fault. We show that the 2011 Mw9.0 Tohoku earthquake ruptured a fault portion characterized by unusually small variations in static shear strength. This observation is consistent with the hypothesis that large earthquakes preferentially rupture regions with relatively homogeneous shear strength. With increasing constraints on the different parameters at play, our approach could, in the future, help identify favorable locations for large earthquakes.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Imaging shear strength along subduction faults
Series title Geophysical Research Letters
DOI 10.1002/2017GL075501
Volume 44
Issue 22
Year Published 2017
Language English
Publisher AGU
Contributing office(s) Earthquake Science Center
Description 11 p.
First page 11329
Last page 11339