Ukinrek maars

Ukinrek maars
Map
Highest point
Elevation299 ft (91 m)
Coordinates57°49′54″N 156°30′35″W / 57.83167°N 156.50972°W / 57.83167; -156.50972[1]
Geography
LocationBecharof National Wildlife Refuge, Alaska, on Alaska Peninsula
Parent rangeAleutian Range
Geology
Mountain typeMaars
Last eruptionMarch–April 1977

The Ukinrek maars (Central Yupik: Ukinrek[2]) are two volcanic craters on the north side of the Aleutian Range in Alaska that were formed by a phreatomagmatic eruption in 1977. The maars are 1.5 km south of Becharof Lake and 12 km northwest of Peulik Volcano, on a low area of the range, bordering the Bering Sea. The western of the two is elliptical in shape and up to 170 m in diameter and 35 m deep. The other lies 600 m to the east and is circular and up to 300 m in diameter and 70 m deep. The east maar has a 49 m-high lava dome within its crater lake.[3]

The eruption occurred in March–April 1977 and lasted for ten days. There was no previous eruption. The magmatic material was olivine basalt from a mantle source. Pyroclastic surge from the eruptions traveled to the northwest.[1] The volume of lava erupted was 9×105 m3 and the volume of tephra expelled was 2.6×107 m3.[4] They were named shortly after the eruptions and the literal translation means "Two Holes".[2][5]

The Quaternary age Gas Rocks dacite domes some three km to the northeast were the site of a phreatic eruption some 2300 years ago.[1]

Ukinrek eruption in April 1977
Map showing volcanoes of Alaska
  1. ^ a b c "Ukinrek Maars". Global Volcanism Program. Smithsonian Institution. Retrieved 2021-06-28.
  2. ^ a b Kienle, Juergen; Kyle, Philip; Self, Stephen; Motyka, Roman; Lorenz, Volker (February 1980). "Ukinrek Maars, Alaska, I. April 1977 eruption sequence, petrology and tectonic setting". Journal of Volcanology and Geothermal Research. 7 (1–2): 11. Bibcode:1980JVGR....7...11K. doi:10.1016/0377-0273(80)90018-9. Retrieved 1 May 2024.
  3. ^ Miller, T.P., et al., 1998, Catalog of the historically active volcanoes of Alaska: U.S. Geological Survey Open-File Report 98-0582, 104 p
  4. ^ "Ukinrek Maars: Eruptive History". Global Volcanism Program. Smithsonian Institution. Retrieved 2021-06-28.
  5. ^ "Ukinrek Maars". Alaska Volcano Observatory. Retrieved 1 May 2024.