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Aftershock area expansion and mechanical heterogeneity of fault zone within subduction zones

Tajima, Fumiko and Kanamori, Hiroo (1985) Aftershock area expansion and mechanical heterogeneity of fault zone within subduction zones. Geophysical Research Letters, 12 (6). pp. 345-348. ISSN 0094-8276. doi:10.1029/GL012i006p00345.

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We investigate global variations in the pattern of aftershock area expansion associated with large subduction zone earthquakes. The expansion of aftershock areas with time is relatively small in the subduction zones of Alaska, the Aleutians, Mexico, and parts of the Kuriles and South America. These subduction zones are interpreted to be characterized by moderate to strong interplate coupling. In contrast, the extent of aftershock expansion is greater for events within the subduction zones of northeast Japan and western and south Pacific where interplate coupling is inferred to be weak. These results are interpreted in terms of an asperity model where a fault zone is represented by a distribution of strong spots (asperities) and weaker zones. The immediate aftershock area is assumed to extend over an area occupied by asperities, and the subsequent expansion to occur into the surrounding weaker zones. If large asperities abut each other on a fault plane, interplate coupling is strong and little expansion of aftershock area occurs. Smaller and more sparsely distributed asperities cause weak interplate coupling and significant expansion of aftershock area. Small and densely distributed asperities result in moderate interplate coupling and little aftershock expansion.

Item Type:Article
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Kanamori, Hiroo0000-0001-8219-9428
Additional Information:Copyright 1985 by the American Geophysical Union. (Received April 9, 1985; accepted April 23, 1985) Paper number 5L6534. We thank Steven Wesnousky, Chris Sanders, Larry Ruff, and Luciana Astiz for critical comments on the manuscript. This research was partially supported by NSF Grants EAR 81-16023 and EAR83-12890 and USGS contract #14-08-001-G-979. Contribution 620, Institute for Geophysics, University of Texas at Austin; and contribution 4215, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California.
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NSFEAR 81-16023
NSFEAR 83-12890
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University of Texas at Austin, Institute of Geophysics620
Caltech Division of Geological and Planetary Sciences4215
Issue or Number:6
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ID Code:51058
Deposited By: George Porter
Deposited On:30 Oct 2014 18:09
Last Modified:10 Nov 2021 19:05

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