2018/11/19 by Rob Witter, Robert C. Witter, Richard W. Briggs +12 · 2 citations
Earth and Planetary Sciences · #Geology and Paleoclimatology Research #earthquake and tectonic studies #Geological and Geochemical Analysis
paper · doi:10.1130/b32031.1
Research Article| November 16, 2019 Evidence for frequent, large tsunamis spanning locked and creeping parts of the Aleutian megathrust Rob Witter; Rob Witter † 1Alaska Science Center, U.S. Geological Survey, 4210 University Drive, Anchorage, Alaska 99508, USA †[email protected] Search for other works by this author on: GSW Google Scholar Rich Briggs; Rich Briggs 2Geological Hazards Science Center, U.S. Geological Survey, 1711 Illinois Street, Golden, Colorado 80401, USA Search for other works by this author on: GSW Google Scholar Simon E. Engelhart; Simon E. Engelhart 3Department of Geosciences, University of Rhode Island, 9 East Alumni Avenue, Kingston, Rhode Island 02881, USA Search for other works by this author on: GSW Google Scholar Guy Gelfenbaum; Guy Gelfenbaum 4Pacific Coastal and Marine Science Center, U.S. Geological Survey, 400 Natural Bridges Drive, Santa Cruz, California 95060, USA Search for other works by this author on: GSW Google Scholar Rich D. Koehler; Rich D. Koehler 5Nevada Bureau of Mines and Geology, Mail Stop 178, University of Nevada, Reno, Nevada 89557, USA Search for other works by this author on: GSW Google Scholar Alan Nelson; Alan Nelson 2Geological Hazards Science Center, U.S. Geological Survey, 1711 Illinois Street, Golden, Colorado 80401, USA Search for other works by this author on: GSW Google Scholar SeanPaul La Selle; SeanPaul La Selle 4Pacific Coastal and Marine Science Center, U.S. Geological Survey, 400 Natural Bridges Drive, Santa Cruz, California 95060, USA Search for other works by this author on: GSW Google Scholar Reide Corbett; Reide Corbett 6Department of Geological Sciences, East Carolina University, 101 Graham Building, Greenville, North Carolina 27858, USA Search for other works by this author on: GSW Google Scholar Kristi Wallace Kristi Wallace 7U.S. Geological Survey, Alaska Volcano Observatory, 4230 University Drive, Suite 100 Anchorage, Alaska 99508, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2019) 131 (5-6): 707–729. https://doi.org/10.1130/B32031.1 Article history received: 12 Feb 2018 rev-recd: 05 Jul 2018 accepted: 21 Aug 2018 first online: 16 Nov 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Rob Witter, Rich Briggs, Simon E. Engelhart, Guy Gelfenbaum, Rich D. Koehler, Alan Nelson, SeanPaul La Selle, Reide Corbett, Kristi Wallace; Evidence for frequent, large tsunamis spanning locked and creeping parts of the Aleutian megathrust. GSA Bulletin 2019;; 131 (5-6): 707–729. doi: https://doi.org/10.1130/B32031.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract At the eastern end of the 1957 Andreanof Islands, Alaska, USA, moment magnitude 8.6 earthquake rupture, Driftwood Bay (Umnak Island) and Stardust Bay (Sedanka Island) lie along presently locked and creeping parts of the Aleutian megathrust, respectively, based on satellite geodesy onshore. Both bays, located 200 km apart, face the Aleutian trench and harbor coastal evidence for tsunami inundation in 1957. Here we describe the evidence at Driftwood Bay, including eight sheets of landward-fining, normally-graded marine sand that extend up to 375 m inland and 23 m above mean tide level. Drift logs that corroborate historical accounts of 1957 tsunami runup on Umnak Island's Pacific coast overlie the youngest sand sheet, which 137Cs activity shows was deposited in the decade before 1963. The older sand sheets probably record tsunamis prior to 1957 because an emergent coastal terrace lacks evidence for storm-wave erosion and overwash since ca. 2 ka. Comparisons of the Driftwood Bay and Stardust Bay tsunami histories suggest that at least twice in the past 1700 years inundation occurred at one site but not the other. In contrast, Bayesian age-depth modeling suggests that the two bays may record five tsunamis like the 1957 tsunami, generated by earthquake ruptures that spanned the presently locked and creeping parts of the Aleutian megathrust. However, serial tsunamis occurring within days to centuries cannot be precluded. Our findings imply 164–257-year recurrence intervals for large eastern Aleutian tsunamis and challenge the notion that creeping parts of the megathrust, inferred from geodesy onshore, pose lower earthquake and tsunami hazards than locked areas. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.