Ukinrek Maars
Maar(s) in United States
Key Facts
Elevation
91 m (299 ft)
Type
Maar(s)
Location
57.834°, -156.520°
Region
Alaska Peninsula Volcanic Arc
Rock Type
Basalt / Picro-Basalt
Tectonic Setting
Subduction zone
Location
Loading map...
Overview
Ukinrek Maars are two explosion craters that were created in an area without previous volcanic activity during a 10-day phreatomagmatic eruption March-April 1977. The basaltic maars were erupted through glacial deposits in the Bering Sea lowlands 1. 5 km S of Becharof Lake and 12 km W of Peulik volcano; their location is related to the regional Bruin Bay fault.
The elliptical West Maar, which was the first to form, is 105 x 170 m and 35 m deep. The other maar, 600 m to the east, is 300 m wide and 70 m deep. Both maars are now filled by crater lakes; the eastern lake encircles a 49-m-high lava dome that was emplaced at the end of the eruption.
Base surges were directed primarily to the NW. Juvenile material from the Ukinrek eruptions was of mantle-derived olivine basaltic composition. The dacitic Gas Rocks lava domes, of Quaternary age, are located on the shores of Becharof Lake, 3 km N of Ukinrek maars and were the site of a phreatic eruption about 2,300 years ago.
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 | 49 years ago | Recent | Recently active |
Monitoring & Alert Status
Monitoring Networks
Current Status
Nearby Volcanoes in North America Volcanic Regions
Quick Info
- •Smithsonian ID: 312131
- •Evidence: Eruption Observed
- •Epoch: Holocene
About the Photo
Ukinrek Maars are two phreatomagmatic explosion craters that were created in an area without previous volcanic activity during a 10-day-long eruption that began on 30 March 1977. A greenish lake fills East Maar, the largest of the two in this 1994 view from the south. The smaller West Maar is surrounded by dark tephra near the left margin. Gas Rocks, an older volcanic center, forms the peninsula extending into Becharof Lake in the background.
Photo by Chris Nye, 1994 (Alaska Division of Geological and Geophysical Surveys, 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.