Okmok Volcano - John Seach


Aleutian Islands, Alaska

53.42 N, 168.13 W
summit elevation 1073 m
Shield Volcano

The volcano is located in the NE of Umnak Island in the eastern Aleutian Islands. The summit contains nested calderas.

2008 Eruption
An explosive eruption occurred at Okmok volcano, Aleutian Islands, on 12th July 2008. The eruption was preceded by an hour by earthquake activity. Residents of Umnak Island heard explosions accompany the eruption. Ash emissions reached 50,000 ft altitude. Heavy ashfall occurred on eastern Umnak Island. Residents of the island were evacuated by helicopter and boat to Unalaska.

1997 Eruption
An eruption began on 13th February 1997 from a cone on the south side of the caldera floor. There was an ash plume to 10 km altitude, and a lava flow 6 km long.

1986-88 Eruptions
An ash eruption began on 18th November 1986. On 31st January 1987 a mushroom-like cloud was observed at the volcano. On 26th February 1988, ash emissions occurred from a new vent at the SW base of the cone.

Okmok Volcano Eruptions

2008, 1997, 1986-88, 1983, 1981, 1960-61, 1958, 1945, 1943, 1938, 1936?, 1931,
1899, 1878, 1824-30, 1817-20, 1805