Volcanoes: Danger lurks across the inlet

Posted: Saturday, May 26, 2001

Cook Inlet's volcanoes look serene and majestic, but beneath their icy mantles burn hearts of fire. Although they are quiet now, they could erupt at any time.

The Chigmit Mountains, the range across from the Kenai Peninsula, includes some of the world's most active volcanoes. They link the Aleutian chain with the Alaska Range, North America's tallest peaks.

Southcentral Alaska sits on the "Ring of Fire," a string of volcanic and seismic hot spots that circle the Pacific Ocean.

Beneath the Gulf of Alaska, the North Pacific geologic plate slides beneath the continental shelf about as fast as fingernails grow, pushing up the young mountains of outer Kenai, Kodiak and Prince William Sound. The buried crust breaks up in the planet's molten interior. The melting zone generates lava that pushes toward the surface miles to the northwest.

Alaska volcanoes spew not lava but plumes of airborne ash and avalanches of hot rocks, ash and boiling mud that tumble down their slopes. Inlet volcanoes have had numerous historic eruptions, blanketing the ground with powdery ash and endangering aircraft.

The Alaska Volcano Observatory in Anchorage monitors the region. It posts information about the peaks and updates on their activity on its Web site at fm.gi.alaska.edu/.

Plans are pending to build a North Pacific Volcano Learning Center near Stariski Creek between Ninilchik and Anchor Point. The proposed facility would include public educational displays and monitoring programs.

Redoubt Volcano, the 10,197-foot symmetrical peak that dominates the western horizon from the central peninsula, was the most recent to erupt. Beginning Dec. 14, 1989, and extending into 1990, it sent mushroom clouds of ash to an altitude of 12 miles. The eruption shut down air traffic and threatened the Drift River Oil Terminal. It also erupted from 1966 to 1968.

Iliamna Volcano, 10,016-feet tall and just south of Redoubt, has been quiet in historic times. Glaciers radiate from its rambling multiple peaks.

Augustine Volcano near Homer occupies its own island in Kamishak Bay. The cone rises 4,025 feet. Young and restless, Augustine erupted in 1963, 1976 and 1986. It poses an additional threat because its unstable dome could break apart, fall into the sea and generate a tsunami.

Mount Douglas is the southernmost inlet volcano. The 7,000-foot peak has not erupted in historic times, but scientists report activity since the last ice age.

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