Late Holocene great earthquakes in the eastern part of the Aleutian megathrust

Shennan, I.; Bruhn, R.; Barlow, N.L.M.; Good, K.; Hocking, E.P.

doi:10.1016/j.quascirev.2013.11.010

Late Holocene great earthquakes in the eastern part of the Aleutian megathrust Thumbnail

Authors

I. Shennan

R. Bruhn

N.L.M. Barlow

K. Good

E.P. Hocking

Abstract

The great earthquake, Mw 9.2, of AD 1964 may not be typical of other megathrust earthquakes in the region during the last 4000 years. We present new field data from three sites: Copper River Delta, the lower Katalla River valley and Puffy Slough, to enhance the temporal and spatial resolutions of the paleoseismic records of multiple great earthquakes. Differences in the spatial patterns of coseismic uplift and subsidence suggest different rupture combinations of the Kodiak, Prince William Sound and western Yakutat segments of the plate boundary. The longest and most comprehensive records all come from the Prince William Sound segment. Most sites here reveal net subsidence over multiple earthquake cycles except where probable upper plate faulting contributes locally to net uplift, with measurable differences between sites only a few kilometers apart. We identify the Katalla area as a source of local seismic hazard, similar to other locations in the western part of the Yakutat microplate, including the two Mw8+ ruptures in AD 1899. We use a Bayesian radiocarbon modeling approach to estimate the age and recurrence intervals of multiple great earthquakes for the Prince William Sound segment of the megathrust. The long interval, 883 ± 34 (2σ) years, between the penultimate earthquake and AD 1964 contrasts with the older earthquakes that have intervals ranging from ~420 to ~610 years, with a mean of ~535 years.

Citation

Shennan, I., Bruhn, R., Barlow, N., Good, K., & Hocking, E. (2014). Late Holocene great earthquakes in the eastern part of the Aleutian megathrust. Quaternary Science Reviews, 84, 86-97. https://doi.org/10.1016/j.quascirev.2013.11.010

Journal Article Type	Article
Publication Date	Jan 15, 2014
Deposit Date	Nov 19, 2013
Publicly Available Date	Apr 22, 2014
Journal	Quaternary Science Reviews
Print ISSN	0277-3791
Publisher	Elsevier
Peer Reviewed	Peer Reviewed
Volume	84
Pages	86-97
DOI	https://doi.org/10.1016/j.quascirev.2013.11.010
Keywords	Quaternary, Sea level, Paleoseismology, Alaska.

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Copyright Statement
NOTICE: this is the author’s version of a work that was accepted for publication in Quaternary Science Reviews. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Quaternary Science Reviews, 84, 2014, http://dx.doi.org/10.1016/j.quascirev.2013.11.010.