Albay province residents were warned Saturday about a "possible eruption" of Mt. Mayon after the Philippine Institute of Volcanology and Seismology (Phivolcs) observed upward movements of magma.

Phivolcs Director Renato Solidum said that recent activities in Mayon volcano such as intensified crater glow, low frequency volcanic eruption, and ground uplift, point to a possible eruption.

"Malayo pa na pumutok ang Mayon since nasa Alert Level No. 2 pa lang ito na ang ibig sabihin ay may moderate unrest. But there's a possibility that it might eventually lead to an eruption," Solidum said.

Phivolcs earlier heightened the alert status on Mayon from low-level unrest (1) to moderate unrest (2) after observing intensified glow at the crater.

An aerial survey conducted by volcanologists last week saw a "cone-shaped pile of hot steaming old rocks" that they said could be possible remnants from previous eruptions and the source of glow at the crater.

Phivolcs added that low frequency volcanic eruptions could indicate that fresh volcanic materials are moving upward causing the formation of the cone-shaped pile of hot materials at the crater.

Beginning last month, Phivolcs said, monitors indicated an increase in the current activities of Mayon volcano.

It added that the number of recorded low- frequency volcanic earthquakes also rose to a higher level which signified movement of magma beneath the volcano edifice at shallow depth.

But Phivolcs clarified that the present seismic count is at the same level of low-level unrest when a phreatic explosion occurred in August last year.

Phivolcs science research specialist Jojo Cordon said that a phreatic explosion occurs when rising magma makes contact with ground or surface water.

Last June, Phivolcs measured a ground uplift of about one centimeter that was sustained in a resurvey conducted last week.