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Thrust-type subduction-zone earthquakes and seamount asperities; a physical model for seismic rupture

Mark Cloos
Thrust-type subduction-zone earthquakes and seamount asperities; a physical model for seismic rupture
Geology (Boulder) (July 1992) 20 (7): 601-604

Abstract

A thrust-type subduction-zone earthquake of M (sub w) 7.6 ruptures an area of approximately 6000 km (super 2) , has a seismic slip of approximately 1 m, and is nucleated by the rupture of an asperity approximately 25 km across. A model for thrust-type subduction-zone seismicity is proposed in which basaltic seamounts jammed against the base of the overriding plate act as strong asperities that rupture by stick-slip faulting. A M (sub w) 7.6 event would correspond to the near-basal rupture of a approximately 2-km-tall sea-mount. The base of the seamount is surrounded by a low shear- strength layer composed ofsubducting sediment that also deforms between seismic events by distributed strain (viscous flow). Planar faults form in this layer as the seismic rupture propagates out of the seamount at speeds of kilometres per second. The faults in the shear zone are disrupted after the event by aseismic, slow viscous flow of the subducting sediment layer. Consequently, the extent of fault rupture varies for different earthquakes nucleated at the same seamount asperity because new fault surfaces form in the surrounding subducting sediment layer during each fast seismic rupture.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 20
Serial Issue: 7
Title: Thrust-type subduction-zone earthquakes and seamount asperities; a physical model for seismic rupture
Author(s): Cloos, Mark
Affiliation: Univ. Tex. at Austin, Dep. Geol. Sci., Austin, TX, United States
Pages: 601-604
Published: 199207
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 22
Accession Number: 1992-034525
Categories: Solid-earth geophysicsSeismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch map
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1992
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