wunderground.com By: Becky Oskin Published: May 3, 2013
USGS The 2009 eruption of Alaska's Redoubt volcano.
Before Alaska's Redoubt volcano erupted with an incredible series of explosions in March 2009, the mountain kept residents on edge for months.
The volcano first signaled its unrest in fall 2008 with tremors that hinted at magma moving deep underground. By January 2009, an uptick in tremors, earthquakes and gas emissions from Redoubt volcano led the U.S. Geological Survey's Alaska Volcano Observatory to raise its threat level to orange, stating an eruption was imminent. (The highest threat is red.) But to the confusion of some Alaskans, the volcano observatory, following national criteria for alerts, lowered and raised Redoubt's threat level between yellow and orange several times before hitting red on eruption day, March 22.
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