Eruption of Mount Redoubt Volcano Continues with a Another Major Explosion

Photograph of Redoubt's March 27, 19:25 eruption cloud, as seen from near Homer. Photograph courtesy of Dennis Anderson. Mount Redoubt Volcano, 106 miles southwest of Anchorage, Alaska, erupted again explosively March 26, 2009, at approximately 09:24 AKDT, sending ash as high as 65,000 feet into the air. On March 25, 2009 at 06:07:51, a small explosion occurred at Redoubt volcano at 05:12 AKDT (1312 UTC). The cloud height was estimated to be about 15,000 ft and was drifting north to northwest of the volcano. The event lasted about 10 minutes. On March 24, at 21:58:46, the rate of seismicity significantly declined. Small discrete earthquakes occurried at a rate of about 10 per hour. A sixth explosive eruption occurred on March 23 at 7:41PM AKDT. As of March 22, 2009, at approximately 10:38 PM AKDT, had a total of 6 explosive events that sent ash more than 50,000 feet into the air, including one Monday evening at 7:41 PM AKDT. Ashy sunset from Soldotna taken March 27, 2009. Photo courtesy of Isaak, Sharon On Sunday, March 22, 2009 10:56 10:56:25 PM AKDT, an eruption of Mt. Redoubt began at approximately 22:38 AKDT, March 22, 2009 (0638 UTC). At that time the Alaska Volcano Observatory (AVO) raised the aviation color code to Red and the alert level to Warning. Initial height of the eruption cloud was estimated at less than 20,000 ft above sea level. On Saturday, March 21, 2009 10:09 10:09:44 PM AKDT, seismic activity continued to increase and conditions were expected to possibly evolve rapidly culminating in an eruption within days to weeks. Image courtesy of Dennis Anderson, http://www.auroradude.com During an abrupt increase in seismicity on Sunday, March 15, AVO raised the color code and alert level to ORANGE/Warning and following a burst of steam and ash that was observed by airborne AVO staff. High volcanic gas emissions were measured during the event. After several hours, seismicity and steam emissions declined, and remained low for the next several days. The color code and alert level was subsequently reduced to YELLOW/Advisory on March 18, 2009. Seismic activity at Redoubt was low over the remainder of the week but remained above background levels. The seismicity consisted of occasional short periods of low amplitude volcanic tremor and small discrete earthquakes. A burst of several dozen larger events occurred Friday morning. Mostly clear weather at the volcano that week provided good satellite and web camera images, and these showed nothing unusual. A steam plume rising just above the summit of the volcano was visible most of the week. AVO continued to monitor Redoubt closely, but the AVO operations center in Anchorage was no longer formally staffed 24 hours per day, although someone was on duty 24 hours per day. Heavily ice-mantled Redoubt volcano is located on the western side of Cook Inlet, 170 km (106 mi) southwest of Anchorage and 82 km (51 mi) west of Kenai, within Lake Clark National Park. Redoubt is a stratovolcano which rises to 10,197 feet above sea level. Recent eruptions occurred in 1902, 1966-68, and 1989-90. The 1989-90 eruption produced mudflows, or lahars, that traveled down the Drift River and partially flooded the Drift River Oil Terminal facility. The ash plumes produced by the 1989-90 eruption affected international air traffic and resulted in minor or trace amounts of ash in the city of Anchorage and other nearby communities. Following the steam and ash emission on Sunday, March 15, seismicity declined to levels prior to that event, and no additional emissions were observed in web camera or satellite Image courtesy of the Alaska Volcano Observatory / U.S. Geological Survey images. The new magma beneath the volcano did not show signs of upward movement at that time. The volcano remained restless with abnormally high rates of gas emission and continued melting of the summit glacier. Scientists still thought it possible for the current period of unrest to result in an eruption. However, the type of unrest observed could persist for many months to a year or more and not lead to an eruption. It was possible for conditions at the volcano to change rapidly, advancing from relatively low levels of activity to eruption in time periods as short as 24 hours or less. AVO continued to monitor Redoubt closely. Editors note: As of press time, AVO was continuing to monitor the activity of Mount Redoubt.