The Alaska Volcano Observatory said Friday afternoon that the eruption of a slowly growing lava dome at Cleveland Volcano in the Aleutian Islands is continuing as it has since it began Tuesday night.
Officials on an August 8 National Oceanic and Atmospheric Administration flyover photographed a small, dark-colored dome centered at the bottom of the summit crater, according to a report on Friday.
In the last clear satellite view of the summit on August 9, the lava dome was about 60 meters (197 feet) in diameter. The dome at the summit has been expanding in diameter over the last several weeks.
The aviation threat level remained color-coded as orange with an eruption watch in effect.
The danger volcanic ash clouds pose to aircraft was highlighted by the Dec. 15, 1989 experience of KLM Flight 867, which inadvertently flew into an ash cloud from a recent eruption of Mount Redoubt. The ash stalled all four of the Boeing 747’s engines and the plane -- along with its 231 passengers -- fell more than two miles before the engines could be restarted for an emergency landing. The aircraft ultimately required $80 million in repairs, including the replacement of the engines.
According to the U.S. Geological Survey, the incident galvanized interest in monitoring the state’s volcanic activity, since ash clouds are difficult to distinguish from normal clouds both visibly and on radar. Those concerns were reinforced by eruptions at Mount Spurr in September 1992, temporarily grounding air traffic across a wide upper swath of the northern U.S. and Canada.
AVO, jointly formed in 1988 by the USGS, the University of Alaska Fairbanks Geophysical Institute and the Alaska Division of Geological and Geophysical Surveys, follows local data and coordinates with scientists in Russia to track eruptions in both nations. The observatory’s assessments, updates and warnings have played a vital role in alerting the public to the locations and effects of ash plumes.
While volcanic events can take place in moments, waiting for them to happen is an experience familiar to many Alaskans. After Mount Redoubt erupted numerous times in the spring of 2009, showering Southcentral Alaska with volcanic ash, Anchorage residents spent weeks with surgical masks and windshield covers at the ready while they followed reports of elevated volcanic activity at Redoubt.
Flights across the Atlantic got a taste of the disruptions a volcanic event can bring when Iceland’s Eyjafjallajökull Volcano erupted in April 2010, creating ash clouds which carried east and grounded aircraft across Europe for weeks.
Cleveland could have similar effects on several of the air corridors which link Alaska to Asia, carrying 20,000 passengers and millions of dollars in cargo each day. The observatory doesn’t have a monitoring network on the volcano’s island, but -- like many Alaskans -- it’s keeping a close eye on activity there.