Alaska’s Redoubt Volcano Erupts with Several Explosions

by Nancy Atkinson on March 23, 2009

Redoubt volcano crater showing rapidly melting glacier and enlarged "ice piston" feature. Picture Date: March 21, 2009  Image Creator: Cyrus Read,  Image courtesy of AVO/USGS.
Overnight, Alaska’s Redoubt volcano erupted with five large explosions. The National Weather Service has issued an Ashfall Advisory, with light ashfall already reported in some regions. Located about 100 miles southwest of Anchorage, Redoubt’s last eruption occurred in 1989-1990, causing widespread mudfalls or “lahars” and coated Anchorage and other nearby areas with ash. The ash affected air traffic as far south as Texas. Redoubt’s 3,108-meter (10,197-foot) peak has been belching steam for several weeks, with seismologists anticipating a possible eruption. Visible evidence of increased volcanic activity appeared at the alaska volcano summit from late January through February. Holes appeared in the ice, and streams of melt water cut across the surface of the Drift Glacier on Redoubt’s north flank.

The four explosions were recorded at 10:38 pm and 11:02 pm local time on March 22, and then at 2:14 am, 1:39 am and 4:37 am local time on March 23.

An Ashfall Advisory for the Susitna Valley means that all will likely be deposited there, and residents are advised to seal windows and doors, protect electronics and cover air intakes and open water supplies.

Redoubt on Feb. 10, 2009. Formosat image © 2009 Dr. Cheng-Chien Liu, National Cheng-Kung University, and Dr. An-Ming Wu, National Space Organization, Taiwan

Redoubt on Feb. 10, 2009. Formosat image © 2009 Dr. Cheng-Chien Liu, National Cheng-Kung University, and Dr. An-Ming Wu, National Space Organization, Taiwan


On January 24, 2008, the Alaska Volcano Observatory reported a pronounced increase in the number and intensity of tremors underneath Redoubt Volcano. Scientists at the observatory interpreted the seismic activity as a sign of unrest, and they raised the possibility of an eruption occurring in the near future. Shallow tremors This image, acquired by the Formosat-2 satellite on February 10, 2009, shows some signs of current activity, as well as evidence of past eruptions. Redoubt’s 3,108-meter (10,197-foot) summit is near image center, casting a deep shadow on the volcano’s crater. Buried under ice are two lava domes, formed during eruptions in 1966 and 1990. Dark holes in the northward-flowing Drift Glacier were formed where hot magma heated rocks underlying the ice. Crevasses on the steeply dropping glacier are also visible. The 6,000-foot hole is a pit in the snow caused by volcanic activity. On February 26, 2009, the Alaska Volcano Observatory observed a small lahar—an avalanche of volcanic matter—flowing from the 6,000-foot hole.

Source: Alaska Volcano Observatory, NASA’s Earth Observatory

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Nancy Atkinson is Universe Today's Senior Editor. She also works with Astronomy Cast, and is a NASA/JPL Solar System Ambassador.

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