Government scientists say one of the Philippines' most active volcanos is showing signs of heightened unrest and an eruption is possible within weeks.

The Philippine Institute of Volcanology and Seismology raised the alert level for Mt. Mayon in eastern Albay province late Monday after recording an escalation of unrest, including a higher-than-normal number of hot rocks falling within a 15-hour period.

Thirty-two low frequency volcanic earthquakes also were recorded at the 2,460-meter (8,070-foot) mountain about 340 kilometers (210 miles) southeast of Manila.

The institute says molten lava and hot volcanic gases have made a glow in the volcano's crater observable.

Mt. Mayon has erupted more than 40 times over the past 400 years.

On May 7, 2013, the volcano spewed ash, killing five climbers, including three Germans near the summit.