Uplift and subsidence reveal a nonpersistent megathrust rupture boundary (Sitkinak Island, Alaska)
Geophysical Research Letters
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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.
Suggested Citation
Briggs, R., Engelhart, S.E., Nelson, A.R., Dura, T., Kemp, A., Haeussler, P.J., Corbett, D., Angster, S.J., Bradley, L., 2014, Uplift and subsidence reveal a nonpersistent megathrust rupture boundary (Sitkinak Island, Alaska): Geophysical Research Letters, v. 41, no. 7, p. 2289-2296, https://doi.org/10.1002/2014GL059380.
Study Area
| 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 |
| Publication Date | April 14, 2014 |
| 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 |
| Country | United States |
| State | Alaska |
| Other Geospatial | Sitkinak Island |