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Breaking the oceanic lithosphere of a subducting slab: The 2013 Khash, Iran earthquake
Author(s) -
Barnhart William D.,
Hayes Gavin P.,
Samsonov Sergey V.,
Fielding Eric J.,
Seidman Lily E.
Publication year - 2014
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 - 10.1002/2013gl058096
Subject(s) - geology , subduction , seismology , lithosphere , slab , mantle (geology) , episodic tremor and slip , interplate earthquake , oceanic crust , crust , mantle wedge , geophysics , tectonics
Large intermediate‐depth, intraslab normal‐faulting earthquakes are a common, dangerous, but poorly understood phenomenon in subduction zones owing to a paucity of near‐field geophysical observations. Seismological and high‐quality geodetic observations of the 2013 M w 7.7 Khash, Iran earthquake reveal that at least half of the oceanic lithosphere, including the mantle and entire crust, ruptured in a single earthquake, confirming with unprecedented resolution that large earthquakes can nucleate in and rupture through the oceanic mantle. A rupture width of at least 55 km is required to explain both Interferometric Synthetic Aperture Radar observations and teleseismic waveforms, with the majority of slip occurring in the oceanic mantle. Combining our well‐constrained earthquake slip distributions with the causative fault orientation and geometry of the local subduction zone, we hypothesize that the Khash earthquake likely occurred as the combined result of slab‐bending forces and dehydration of hydrous minerals along a preexisting fault formed prior to subduction.