Subducting plate geology in three great earthquake ruptures of the western Alaska margin, Kodiak to Unimak

von Huene, Roland, Miller, John J. and Weinrebe, Wilhelm (2012) Subducting plate geology in three great earthquake ruptures of the western Alaska margin, Kodiak to Unimak Geosphere, 8 (3). GES00715.1. DOI 10.1130/GES00715.1.

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Abstract

Three destructive earthquakes along the Alaska subduction zone sourced transoceanic tsunamis during the past 70 years. Since it is reasoned that past rupture areas might again source tsunamis in the future, we studied potential asperities and barriers in the subduction zone by examining Quaternary Gulf of Alaska plate history, geophysical data, and morphology. We relate the aftershock areas to subducting lower plate relief and dissimilar materials in the seismogenic zone in the 1964 Kodiak and adjacent 1938 Semidi Islands earthquake segments. In the 1946 Unimak earthquake segment, the exposed lower plate seafloor lacks major relief that might organize great earthquake rupture. However, the upper plate contains a deep transverse-trending basin and basement ridges associated with the Eocene continental Alaska convergent margin transition to the Aleutian island arc. These upper plate features are sufficiently large to have affected rupture propagation. In addition, massive slope failure in the Unimak area may explain the local 42-m-high 1946 tsunami runup. Although Quaternary geologic and tectonic processes included accretion to form a frontal prism, the study of seismic images, samples, and continental slope physiography shows a previous history of tectonic erosion. Implied asperities and barriers in the seismogenic zone could organize future great earthquake rupture.

Document Type: Article
Additional Information: WOS:000308940300007
Keywords: Geodynamics; Earthquakes, tsunamis, Alaska margin; ST-ELIAS OROGEN; WILLIAM-SOUND EARTHQUAKE; STRAIN ACCUMULATION; ACCRETIONARY WEDGE; TRANSITION FAULT; ZONE STRUCTURE; COSTA-RICA; GULF; SHUMAGIN; BENEATH
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
DOI etc.: 10.1130/GES00715.1
ISSN: 1553-040X
Related URLs:
Expeditions/Models:
Date Deposited: 25 Apr 2012 07:48
Last Modified: 28 Sep 2017 09:17
URI: http://eprints.uni-kiel.de/id/eprint/14079

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