The Ring of Fire: Alaska’s Volcanoes

Posted: Friday, February 09, 2007

Rimming the Pacific Ocean is one of Earth’s most active geological regions, the tectonic plate boundary that’s part of the well-known “Ring of Fire”. Your visit to the Kenai area, and on your journeys to the south peninsula, you have a front row seat to no less than five active volcanic peaks.

Clearly visible within the north-south spine of the Chigmit Mountains across Cook Inlet are the tier of volcanoes that form the easternmost part of the Aleutian volcanic arc. The Alaska Volcano Observatory in Anchorage monitors the area’s volcanic peaks constantly. Information on current activity can be found at the observatory’s Web site at

Volcanoes visible from the Kenai Peninsula, from north to south, are:

Mount Spurr

Height: 11,070 feet, nearly due west of Anchorage. A great view of Mt. Spurr is the focus of your drive toward Captain Cook State Park on the Kenai Spur Highway.

Activity: 1953 and 1992, dumping ash on the city and closing the airport.

Mount Redoubt

Height: 10,197 feet, dominates the western horizon from the central peninsula. A great place to photograph and view the flanks of Redoubt and Spurr is the pullout along Bridge Access Road in Kenai.

Activity: Photos of this peak’s most recent eruption that began with a spectacular burst of ash on Dec. 14, 1989, can be found in many area gift shops as well as the Kenai Visitor and Cultural Center. This eruption lasted into early 1990. Ash clouds reached heights of 12 miles, shutting down air traffic and threatened the Drift River Oil Terminal. It also erupted in 1966 and 1968.

Mount Iliamna

Height: 10,016 feet, south of Redoubt, surrounded by glaciers radiating from its rambling multiple peaks.

Activity: Iliamna has been quiet in historic times.

Mount Augustine

Height: 4,134 feet, occupies its own island in Kamishak Bay about 70 miles due west of the mouth of Kachemak Bay. Capt. James Cook named the mass of land as St. Augustine when sailing past it on St. Augustine’s Day in 1778. According to the Dictionary of Alaska Names by Donald J. Orth, the saint had been dropped, and Orth’s dictionary, also known as Geological Survey Professional Paper 567, lists modern geographic names officially recognized for use on federal maps, but also lists previous official and unofficial geographic names. Of the names that did not adhere to Mt. Augustine: Kamishak Bay’s grumpy peak, Mount Chinabora, Mount St. Augustin, Mount St. Augustine, Mount San Augustine, Pan de Azucar and Pilon de Azucar. Orth’s dictionary says the volcano was named Pan de Azucar, meaning sugar loaf, in 1779 by Don Ignacio Arteaga, a Spanish explorer. Perhaps the volcano’s snowy peak reminded him of sugar-powdered confection.

Activity: Erupted in 1883, 1908, 1935, 1963-64, 1976, 1986 and throughout 2005-06. Of all the Cook Inlet volcanic peaks, Augustine poses the greatest threat of tsunami. Concern surrounds the possibility that during an eruption, its slope could slide into the sea, generating a tsunami aimed at Kachemak Bay. During your travels to both Seward and Homer, take note of the blue tsunami evacuation route signs.

Mount Douglas

Height: 7,020 feet, southernmost inlet volcano.

Activity: By far the most benign of the group, it has not erupted in historic times, but was active during the last Ice Age.

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