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Accelerated pacific plate subduction following interplate thrust earthquakes at the Japan trench

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Title: Accelerated pacific plate subduction following interplate thrust earthquakes at the Japan trench
Authors: Heki, Kosuke Browse this author →KAKEN DB
Mitsui, Yuta Browse this author →KAKEN DB
Keywords: GPS
2003 Tokachi-Oki earthquake
2011 Tohoku-Oki earthquake
earthquake triggering
Issue Date: Feb-2013
Publisher: Elsevier
Journal Title: Earth and Planetary Science Letters
Volume: 363
Start Page: 44
End Page: 49
Publisher DOI: 10.1016/j.epsl.2012.12.031
Abstract: Interplate thrust earthquakes are usually followed by afterslips, and they let the fore-arc move slowly trenchward. However, we do not know if the subducting oceanic plate is accelerated landward after such earthquakes. The westward velocity of Global Positioning System (GPS) stations in NE Japan show gradient decreasing from east to west reflecting the E-W contractional strain built up by the inter-plate coupling. Here we show that such coupling significantly enhanced (∼1.5 times) after the 2003 Tokachi-Oki earthquake (Mw 8.0), Hokkaido, in the segments adjacent to the ruptured fault. The coupling seems to be further enhanced (∼3 times) after the 2011 Tohoku-Oki earthquake (Mw 9.0). It is unlikely that interplate friction suddenly increased over such a large region, and relatively strong pre-2003 coupling there would not allow such enhancements even if full coupling is attained. Hence they are attributable to the temporary acceleration of the Pacific Plate subduction. We propose a simple 2-dimensional model in which down-dip acceleration of the slab let the force balance rapidly recover promoted by a thin low-viscosity layer on the slab surface. The accelerated subduction would account for temporary activations of regional interplate seismicity after megathrust earthquakes.
Rights: Copyright © 2012 Elsevier B.V. All rights reserved
Type: article (author version)
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 日置 幸介

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