Westdahl
Stratovolcano? in United States
Key Facts
Elevation
1,563 m (5,128 ft)
Type
Stratovolcano?
Location
54.516°, -164.650°
Region
Aleutian Ridge Volcanic Arc
Rock Type
Basalt / Picro-Basalt
Tectonic Setting
Subduction zone
Location
Loading map...
Overview
Westdahl is a broad glacier-covered volcano occupying the SW end of Unimak Island. Two peaks protrude from the summit plateau, and a new crater formed in 1978 cuts the summit icecap. The volcano has a somewhat of a shield-like morphology and forms one of the largest volcanoes of the Aleutian Islands.
The sharp-topped, conical Pogromni stratovolcano, 6 km N, rises several hundred meters higher than Westdahl, but is moderately glacially dissected and presumably older. Many satellitic cones of postglacial age are located along a NW-SE line cutting across the summit of Westdahl. Some of the historical eruptions attributed to the eroded Pogromni may have originated instead from Westdahl (Miller et al.
1998). The first historical eruption occurred in 1795. An 8-km-long fissure extending east from the summit produced explosive eruptions and lava flows in 1991.
Volcanic Hazards & Risk Assessment
Primary Hazards
Risk Level
Geological Composition & Structure
Rock Types
Tectonic Setting
Age & Formation
Eruption Statistics & Analysis
| Metric | Value | Global Ranking | Significance |
|---|---|---|---|
| Total Recorded Eruptions | Unknown | Low | Moderately active volcano |
| Maximum VEI | VEI Unknown | Minor | Local impact potential |
| Recent Activity | 34 years ago | Recent | Recently active |
Monitoring & Alert Status
Monitoring Networks
Current Status
Nearby Volcanoes in North America Volcanic Regions
Quick Info
- •Smithsonian ID: 311340
- •Evidence: Eruption Observed
- •Epoch: Holocene
About the Photo
The summit area of Westdahl, located on the southwestern part of Unimak Island in the eastern Aleutians, is seen here from the east. Westdahl Peak (left) and Faris Peak (right) formed on the broad main edifice. The scoria cone in the center was the principal eruption site for the 1991-92 activity, producing the snow-covered lava flow in the foreground. . The sinuous fissure cutting across the glacial icecap from the summit formed in the opening phases of the eruption and produced lava fountaining.
Photo by C.F. Zeillemaker, 1993 (U.S. Fish and Wildlife Service, courtesy of Alaska Volcano Observatory).
Authority Sources
Related Volcanoes
Basic Information
This page shows basic data from the Smithsonian Global Volcanism Program. For more detailed information, visit the official Smithsonian page.