Amak Island, Bering Sea

Amak Island, Bering Sea

by | Oct 5, 2022

Amak is a volcanic island situated in the Bering Sea that measures about 2 miles (3.2 km) wide and nearly 3 miles (4.8 km) longitudinally, about 172 miles (277 km) northeast of Dutch Harbor and 22 miles (35 km) northwest of Cold Bay, Alaska. The name was first published as ‘Ostrov Amak’ or ‘Amak Island’, by Mikhail Tebenkov of the Imperial Russian Navy, which according to Richard H. Geoghegan, comes from the Alutiiq word ‘amaq’ meaning ‘blood’. Access to the island is restricted to boats and only with a special permit from the Alaska Maritime National Wildlife Refuge that manages the Aleutian Islands Wilderness. 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, and 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, about 770 miles (1,239 km) north of Amak Island. These maars range in size from 13,000 to 26,000 feet (4,000-8,000 m) in diameter with depths up to 980 feet (300 m). These formed during eruptions that 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 an explosive reaction when magma came into contact with permafrost. Hydromagmatic eruptions are violently explosive since permafrost melts slowly and provides a steady source of water to the eruption while keeping the water-to-magma ratio low. Examples of the Seward Peninsula maars include North Killeak Maar, South Killeak Maar, Devil Mountain Maar, and Whitefish Maar. Unlike the maars on the Seward Peninsula that formed lakes, the maar on Amak Island is dry, probably resulting from the porous underlying rock so that a lake was unable to form.

Steller sea lions use reefs surrounding Amak Island for haulouts and an isolated rock islet about 1 mile (1.6 km) north of the island serves as a sea lion rookery. In the 1950s, the worldwide abundance of Steller sea lions was estimated at 240,000 to 300,000 animals, with a range that stretched across the Pacific rim from southern California, Canada, Alaska, and into Russia and northern Japan. By 1990, the U.S. portion of the population had declined by about 80%, which prompted the listing of the Steller sea lion as threatened under the Endangered Species Act. In 1997, with the availability of new genetic information, two distinct populations were designated. A western population extends from Japan around the Pacific rim to Cape Suckling in Alaska near Kayak Island. An eastern population extends from Cape Suckling east to British Columbia and south to California. The western population has continued to decline and the status was changed to endangered. The eastern population has been increasing with the greatest increases in southeast Alaska and British Columbia, but generally poor recovery in California has caused the population to remain listed as threatened. Read more here and here. Explore more of Amak Island here:

About the background graphic

This ‘warming stripe’ graphic is a visual representation of the change in global temperature from 1850 (top) to 2022 (bottom). Each stripe represents the average global temperature for one year. The average temperature from 1971-2000 is set as the boundary between blue and red. The color scale goes from -0.7°C to +0.7°C. The data are from the UK Met Office HadCRUT4.6 dataset. 

Credit: Professor Ed Hawkins (University of Reading). Click here for more information about the #warmingstripes.

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