Mount Redoubt

Mount Redoubt volcano erupted four times overnight, sending an ash plume more than 9 miles into the air in the volcano's first emission in nearly 20 years. Residents in the state's largest city was spared from falling ash, though fine gray dust was falling Monday morning on small communities north of Anchorage.

Ash from Alaska's volcanos is like a rock fragment with jagged edges and has been used as an industrial abrasive. It can injure skin, eyes and breathing passages. The young, the elderly and people with respiratory problems are especially susceptible to ash-related health problems. Alaska Airlines on Monday canceled 19 flights in and out of the Anchorage international airport because of the ash.

Elmendorf Air Force Base in Anchorage told only essential personnel to report to work. The Air Force says 60 planes, including fighter jets, cargo aircraft and a 747 commercial plane, were being sheltered. The first eruption, in a sparsely area across Cook Inlet from the Kenai Peninsula, occurred at 10:38 p.m. Sunday and the fourth happened at 1:39 a.m. Monday, according to the Alaska Volcano Observatory.