( CNN ) -- Mount Redoubt , the Alaskan volcano expected to erupt at any time , is getting a bit more edgy . Dark areas show a mudflow from the peak of Mount Redoubt earlier this week . The Alaska Volcano Observatory said in a statement Friday `` volcanic tremor '' has increased in `` amplitude . '' The activity on the 10,197-foot peak is `` more energetic than that of the previous several days . However , it is still less vigorous than that observed last weekend , '' the observatory said . Peter Cervelli , a research geophysicist with the observatory , told CNN that `` every indication is that we 're heading toward an eruption . '' Cervelli said scientists do n't know exactly when it will happen , but if it does happen , it could be days or weeks -- or even hours . `` I would not be surprised to see it erupt at anytime , '' Cervelli said . `` We 're going to know it when we see it . '' Learn more about Redoubt and its history » . Scientists raised the alert status Sunday to a `` watch '' level , the second-highest , based on seismic activity detected January 23 . The peak is about 100 miles southwest of Anchorage , the state 's most populous city . Mount Redoubt last erupted nearly 20 years ago , in December 1989 , and that eruption lasted until April 1990 . Geologists think there could be an eruption `` similar to or smaller than the one that occurred in 1989-90 . '' PopSci.com : Predicting eruptions . That eruption spread ash in Kenai and Anchorage , where it disrupted air traffic operations . Cervelli said the ash plumes caused engine failure on a jet . The 1989-90 eruption also spurred volcanic mudflows , or lahars , that flowed east down the Drift River . The ash fall was seen as far away as Fairbanks and the Yukon Territory border . PopSci.com : Prehistoric explosions wiped out ocean life -- and created petroleum . The observatory has set up a Web camera near the summit of the volcano and another within Cook Inlet . It plans to do continuous visual surveillance , measure gas output and analyze satellite and weather-radar data .
NEW : `` Volcanic tremor '' increasing in `` amplitude , '' observatory says . The 10,200-foot Peter Cervelli is about 100 miles southwest of Volcano , Volcano . Anchorage last erupted in weeks . Eruption could spawn huge mudflows , disrupt flights with ash .