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Uplift and subsidence reveal a nonpersistent megathrust rupture boundary (Sitkinak Island, Alaska)

Geophysical Research Letters

By:
, , , , , , , ,
DOI: 10.1002/2014GL059380

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Abstract

We report stratigraphic evidence of land-level change and tsunami inundation along the Alaska-Aleutian megathrust during prehistoric and historical earthquakes west of Kodiak Island. On Sitkinak Island, cores and tidal outcrops fringing a lagoon reveal five sharp lithologic contacts that record coseismic land-level change. Radiocarbon dates, 137Cs profiles, CT scans, and microfossil assemblages are consistent with rapid uplift ca. 290-0, 520-300, and 1050-790 cal yr BP, and subsidence in AD 1964 and ca. 640-510 cal yr BP. Radiocarbon, 137Cs, and 210Pb ages bracketing a sand bed traced 1.5 km inland and evidence for sudden uplift are consistent with Russian accounts of an earthquake and tsunami in AD 1788. The mixed uplift and subsidence record suggests that Sitkinak Island sits above a non-persistent boundary near the southwestern limit of the AD 1964 Mw 9.2 megathrust rupture.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Uplift and subsidence reveal a nonpersistent megathrust rupture boundary (Sitkinak Island, Alaska)
Series title:
Geophysical Research Letters
DOI:
10.1002/2014GL059380
Volume
41
Issue:
7
Year Published:
2014
Language:
English
Publisher:
Wiley
Contributing office(s):
Geologic Hazards Science Center
Description:
8 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geophysical Research Letters
First page:
2289
Last page:
2296
Number of Pages:
8
Country:
United States
State:
Alaska
Other Geospatial:
Sitkinak Island