Unusually large tsunamis frequent a currently creeping part of the Aleutian megathrust
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Abstract
Current models used to assess earthquake and tsunami hazards are inadequate where creep dominates a subduction megathrust. Here we report geological evidence for large tsunamis, occurring on average every 300–340 years, near the source areas of the 1946 and 1957 Aleutian tsunamis. These areas bookend a postulated seismic gap over 200 km long where modern geodetic measurements indicate that the megathrust is currently creeping. At Sedanka Island, evidence for large tsunamis includes six sand sheets that blanket a lowland facing the Pacific Ocean, rise to 15 m above mean sea level, contain marine diatoms, cap terraces, adjoin evidence for scour, and date from the past 1700 years. The youngest sheet, and modern drift logs found as far as 800 m inland and >18 m elevation, likely record the 1957 tsunami. Modern creep on the megathrust coexists with previously unrecognized tsunami sources along this part of the Aleutian Subduction Zone.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Unusually large tsunamis frequent a currently creeping part of the Aleutian megathrust |
| Series title | Geophysical Research Letters |
| DOI | 10.1002/2015GL066083 |
| Volume | 43 |
| Issue | 1 |
| Year Published | 2016 |
| Language | English |
| Publisher | American Geophysical Union |
| Contributing office(s) | Alaska Science Center Geology Minerals |
| Description | 9 p. |
| First page | 76 |
| Last page | 84 |
| Country | United States |
| State | Alaska |
| Other Geospatial | Aleutian Islands |
| Online Only (Y/N) | N |
| Additional Online Files (Y/N) | N |
| Google Analytic Metrics | Metrics page |