Amak Island, Bering Sea

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Amak Island, Bering Sea

by | Nov 20, 2019

Amak Island is a volcano about 3 miles (5 km) across in the Bering Sea, 9 miles (14.5 km) off the north coast of the Alaska Peninsula at Izembek Lagoon, 20 miles (32 km) northwest of the community of Cold Bay, and 622 miles (1,003 km) southwest of Anchorage, Alaska. The Alutiiq name was first published as “Ostrov Amak” or ”Amak Island,” by Mikail Tebenkov of the Imperial Russian Navy, which according to R.H. Geoghegan, comes from the word “amaq” meaning “blood”. Access to the island is restricted to only boats with a special permit from the Alaska Maritime National Wildlife Refuge.

Amak Island is a basaltic-andesite stratovolcano with lava flows that stream from the summit. Three historical eruptions have been documented, the first in circa 2550, the second between 1700 and 1710, the most recent in 1796. Each eruption produced lava flows, and the two most recent included a crater eruption. A dry maar is at the edge of an eroding bluff on the southwest plain of the island. This was formed from an explosion that occurred when groundwater came into contact with hot lava or magma.

The largest known maars are found on the Seward Peninsula in northwest Alaska. These maars range in size from 13,000 to 26,000 feet (4,000 to 8,000 m) in diameter and a depth up to 980 feet (300 m). These eruptions occurred over a period of about 100,000 years, with the youngest (the Devil Mountain Maar) occurring about 17,500 years ago. Their large size is due to the explosive reaction that occurs when magma comes into contact with permafrost. Hydromagmatic eruptions are increasingly explosive since permafrost melts slowly and provides a steady source of water to the eruption while keeping the water to magma ratio low. This produces the prolonged, explosive eruptions that created these large maars. Examples of the Seward Peninsula maars include North Killeak Maar, South Killeak Maar, Devil Mountain Maar, and Whitefish Maar. The dry maar on Amak probably resulted from the porous underlying rock so that a maar lake was unable to form. Read more here and here. Explore more of Amak Island here:

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