Indonesia's rumbling Mount Merapi is spewing volcanic ash, magma has fully covered its crater, and a powerful eruption could come any day, a scientist said Thursday.

Authorities said, however, they were not ready to raise the alert to the highest level, which requires immediate evacuation of villagers living on the slopes of the 9,700-foot peak.

The mountain, one of the most active in Indonesia, is still in phase two, they said.

"It's close to eruption," said Dewi Sri, a vulcanologist at a monitoring post near Merapi's peak.

"The crater is fully covered by magma," she said, predicting "an enormous and dreadful eruption" within days.

Indonesia's official Antara news agency, meanwhile, reported that volcanic debris has begun pouring into Ngargomulyo village in the nearby Central Java district of Magelang.

Local officials contacted by The Associated Press were still trying to confirm the reports.

Merapi is one of at least 129 active volcanoes in Indonesia, which is part of the Pacific "Ring of Fire" — a series of fault lines stretching from the Western Hemisphere through Japan and Southeast Asia.

It last erupted in 1994, sending out a searing cloud of gas that burned 60 people to death. About 1,300 people were killed when it erupted in 1930.