Yunaska
Shield in United States
Key Facts
Elevation
550 m (1,804 ft)
Type
Shield
Location
52.639°, -170.632°
Region
Aleutian Ridge Volcanic Arc
Rock Type
Andesite / Basaltic Andesite
Tectonic Setting
Subduction zone
Location
Loading map...
Overview
The elongated 9 x 23 km Yunaska in the Islands of the Four Mountains group of the Aleutian Islands is comprised of two distinct volcanic centers. The older western center consists of the eroded remnants of four overlapping stratovolcanoes that form a linear, NNE-trending ridge. Cinder cones and fissure-fed lava flows extend from the western end of the complex.
The younger eastern complex consists of a shield volcano capped by two nested calderas. The 3. 5-km-wide Coats caldera is located within an older 10 x 13 km caldera and contains cinder cones and a lava field.
Two areas of youthful lava flows extend down the flank through a gap in the SW caldera rim and cover the upper N flank of the caldera. Vents are found on the flanks of the caldera within a kilometer of its rim. A post-caldera cone is capped by a small summit crater.
The eastern center is presumably the source of eruptions recorded since the early 1800s.
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 | 89 years ago | Historical | Recently active |
Monitoring & Alert Status
Monitoring Networks
Current Status
Nearby Volcanoes in North America Volcanic Regions
Quick Info
- •Smithsonian ID: 311210
- •Evidence: Eruption Observed
- •Epoch: Holocene
About the Photo
The summit caldera rim of Yunaska is seen from an older volcanic center on the western side of the island. The younger eastern complex contains two nested calderas. A young lava flow to the far right descended through a notch in the caldera rim. The peaks in the background are (left-to-right) of Carlisle, Cleveland, and Herbert volcanoes.
Photo by Jim Meyers, 1992 (University of Wyoming, 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.