EAGLE RIVER, Alaska — Alaska's Mount Redoubt continued its volcanic explosions Friday, sending ash clouds as high as 50,000 feet above sea level and prompting drivers to head to the auto parts store for new air filters.

The National Weather Service said most of the ash was expected to fall to the north, but trace amounts of ash from two eruptions on Friday and smaller ones overnight could fall on Anchorage itself.

Since the series of eruptions began Sunday night, the volcano has had several bursts. One on Thursday sent ash 65,000 feet high. The last time the volcano had erupted was during a four-month period in late 1989 and early 1990.

The volcano exploded two more times later Friday, sending ash clouds 40,000 and 51,000 feet high.

Two mudflows produced by the volcano Friday were moving down a slough and tributary toward the Drift River Terminal, where 6.2 million gallons of oil is stored, said Chris Waythomas, a geologist with the Alaska Volcano Observatory.

A concrete-reinforced dike is holding the mud back and protecting the terminal's oil storage tanks from damage.

The Coast Guard said the plan was to keep the oil in the tanks instead of draining it.

"The oil is safe where it is at right now," said Coast Guard Cmdr. Joseph Losciuto.