Alaskans Perpare for Volcanic Eruption
Mount Redoubt, or Redoubt Volcano, is an active stratovolcano in the largely volcanic Aleutian Range of Alaska. The mountain is also the highest within the range, and among the highest peaks in Alaska. The once quiet volcano has begun to roar once again. It's last eruption was in 1989 and geologists suggest that the next one is among us.
The volcano began to erupt on December 15, 1989, and would continue to erupt for over 5 months. Sudden melting of snow and ice by the summit by pyroclastic flows and dome collapses caused lahars, or mudflows, which flowed down the north flank of the mountain. A majority of the mudflows coursed to Cook Inlet, about 35 kilometres (22 mi) from the volcano. The lahars entered a nearby river, worrying officials that they might destroy an oil storage facility positioned along it. Since the lahars were produced repetitively, scientists realized that they could use these to analyze a trial period for a newly developed device proposed to measure the movement of rocks against each other. This device, now known as an Acoustic Flow Monitor, alerts nearby stations to possible lahars.
The eruption also caused an airplane to land, after all four of its engines stalled after the plane flew into a cloud of volcanic ash from the volcano. Damage from the eruption was estimated at $160 million, the second costliest volcanic eruption in United States history. If the lahars had gone much further, they could have easily threatened people in the Cook Inlet area, which contains 60% of Alaska's total population.
Starting on Friday, January 23 2009, the level of seismic activity increased markedly, and on Sunday AVO raised the Aviation Color Code to ORANGE and the Volcano Alert Level to WATCH. On the basis of all available monitoring data AVO regards that an eruption similar to or smaller than the one that occurred in 1989-90 is the most probable outcome. We expect such an eruption to occur within days to weeks.
In response to the current increase in activity, AVO has deployed a web camera approximately 7.5 miles north-northwest of the summit and will install additional seismic equipment at the volcano as weather permits. A second web camera also is pointed at Redoubt from a platform within Cook Inlet. The observatory in Anchorage is currently staffed 24 hours a day. We plan continued visual surveillance of the volcano's summit region, frequent airborne measurements of gas output, and frequent analysis of satellite and weather-radar data.
