Aleutian subduction zone tectonic setting and geologic study area

Tectonic setting of the Aleutian subduction zone. (A)  Near Umnak Island, Alaska, the Pacific Plate is subducting beneath North America at 70 mm/yr (arrow). Violet areas outline aftershocks following 20th century megathrust earthquakes. Blue bars depict 1957 tsunami runup elevations (in meters) reported by eyewitnesses, wrack-line surveys and geological studies. (B)  Location of Driftwood Bay on Umnak Island, Dutch Harbor on Unalaska Island, and Stardust Bay on Sedanka Island. These Islands are part of a group of eastern Aleutian Islands collectively known as the Fox Islands.