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Durham University

Department of Geography

Departmental Research Projects

Publication details

Shennan, I., Bruhn, R., Barlow, N.L.M., Good, K. & Hocking, E.P. Late Holocene great earthquakes in the eastern part of the Aleutian megathrust. Quaternary Science Reviews. 2014;84:86-97.

Author(s) from Durham

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.

Department of Geography