Scientists at the U.S. Geological Survey say Alaska's Mount Redoubt volcano could erupt within days to weeks -- perhaps even hours. The threat level has been raised to orange (the stage just before eruption) due to changes in gas emissions and increased earthquake activity. The Alaska Volcano Observatory is reporting: "Seismic unrest continues at Redoubt and activity is well above normal background levels." Mount Redoubt last erupted nearly 20 years ago, in December 1989 (pictured). Read more at FOXNews.com.