(AP) -- The Mayon volcano, which has blown its top nearly 40 times in 400 years, menaced nearby residents with small eruptions of ash and lava Wednesday as Philippine authorities moved more than 30,000 people to shelters in case of a larger eruption.
Trickles of lava rolled down the 8,070-foot (2,460-meter) mountain towering over the Albay Gulf in the central Philippines, while five new ash explosions, one of them reaching 550 yards (500 meters) in the air, shook Mayon's steep slopes, said chief state volcanologist Renato Solidum.
During the day, the summit is shrouded in white clouds of dust and ash, and dark orange lava becomes clearly visible in the nighttime. Residents of Legazpi city on the foothills of the cone-shaped mountain converge in a downtown park at night to watch the spectacle from a safe distance.
"There is the possibility that it can turn into the explosive phase of the eruption," Solidum told The Associated Press. "Right now, we cannot say for sure, but the initial phases of 2000, 2001 and 2006 eruptions are almost the same."
Scientists raised the alert level on Mayon to two steps below a major eruption after ash explosions late Monday. Albay provincial authorities quickly started moving thousands of families from a five-mile (eight-kilometer) danger zone around the mountain.
More than 30,000 had been transported out of the critical area by Wednesday, or 65 percent of the targeted population, said Cedric Daep, head of the provincial disaster management office.
"We have no more residents inside the danger zone. We are evacuating only those nearby," he said. Defense Secretary Norberto Gonzales had ordered a tight watch to prevent farmers from entering the zone, Daep said. The evacuation area includes three cities and five municipalities.
"It is such a big area. The objective is zero casualty," he said.
Residents in Albay are used to moving away from Mayon. Nearly 50,000 people live in the farming area.
Mayon last erupted in 2006, when about 30,000 people were moved. Another eruption in 1993 killed 79 people.
The first recorded eruption was in 1616 but the most destructive one came in 1814, killing more than 1,200 people and burying a town in mud. The ruins of the church in Cagsawa are among the Philippines' most iconic attractions.
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.
Explore further: Climate change does not cause extreme winters, new study shows