State volcanologists raised the alert level on the cone-shaped, 8,070-foot (2,460-meter) Mayon volcano overnight to two steps below a major eruption after ash explosions.
Dark orange lava fragments glowed in the dark as they trickled down the mountain slope overnight. Renato Solidum, head of the Philippine Institute of Volcanology and Seismology, said the activity could get worse in coming days.
"It's already erupting," Solidum told The Associated Press.
More than 20,000 people were evacuated to safety by nightfall Tuesday, said Gov. Joey Salceda of Albay province, where Mayon is located about 210 miles (340 kilometers) southeast of Manila.
The first of 20 vehicles, including army trucks, were sent to villages to take residents to schools and other temporary housing, provincial emergency management official Jukes Nunez said.
"It's 10 days before Christmas. Most likely people will be in evacuation centers, and if Mayon's activity won't ease down we will not allow them to return to their homes," Nunez said. "It's difficult and sad, especially for children."
Residents in Albay are used to moving away from Mayon. Nearly 50,000 people live in a five-mile (eight-kilometer) radius around the mountain, and some villages were evacuated last month when the volcano spewed ash.
Mayon last erupted in 2006, and about 30,000 people were moved. Another eruption in 1993 killed 79 people.
Mayon's most violent eruption, in 1814, killed more than 1,200 people and buried a town in mud.
The Philippines lies along the Pacific "Ring of Fire," where volcanic activity and earthquakes are common. About 22 out of 37 volcanos in the archipelago are active.
Edited by Palisade, 15 December 2009 - 08:43 PM.