One of the Philippines' most active volcanoes, Mt. Mayon is once again showing signs of heightened unrest and it is expected that the volcano would eruption in the coming days, scientists warned today.

The alert level was raised to "critical" for Mt. Mayon in eastern Albay province late Monday by the Philippine Institute of Volcanology and Seismology. The experts raised the alert level after recording an escalation of unrest within a 15-hour period. The unrest included 39 incidents of hot rocks falling in the summit area and 32 low frequency volcanic earthquakes.

According to scientists, the molten lava and hot volcanic gases have made a glow in the 2,460-meter (8,070-foot) volcano's crater observable.

The activities show "Mayon is exhibiting relatively high unrest and that magma is at the crater and that hazardous eruption is possible within weeks," the institute added in its bulletin.

Meanwhile, Albay Governor Joey Salceda on Monday ordered the evacuation of thousands of residents within a 6- to 8-kilometer (3.7- to 5-mile) radius of the volcano. Disaster councils of the province and the region held an emergency meeting to map out steps to avert casualties, said Jukes Nunez, a disaster management officer in the province.

The volcano institute said that it was important to keep people out of a "permanent danger zone" extending 6 kilometers (3.7 miles) from the mountain and 7 kilometers (4.3 miles) on the southeastern flank.

Mt. Mayon is located about 340 kilometers (210 miles) southeast of Manila and it has erupted more than 40 times over the past 400 years.