Legazpi city: The public is advised to stay calm yet alert amid the recent activity in Mayon Volcano, the head of the Philippine Institute of Volcanology and Seismology (Phivolcs) said on Monday. "Mayon Volcano at Alert Level 3 poses risks for ash fall, rock falls, lava effusion at pyroclastic density currents (PDCs). Stay calm but alert," Phivolcs Director Teresito Bacolcol said in a Bagong Pilipinas Ngayon interview.

According to Philippines News Agency, Bacolcol also reminded the public not to enter the six-kilometer permanent danger zone, to take precaution against ash fall, and heed official advisories. The local government units should continue implementing safety restrictions and be ready in case evacuation is necessary, he said.

Several towns in Albay reported ash fall last Saturday following a strombolian eruption or a moderately explosive and intermittent volcanic burst, following sustained collapse-generated PDCs. The event lasted for over four hours and PDCs reached up to five kilometers from the summit, Bacolcol said.

Ash plume reached 3,000 meters above sea level, and ash reportedly reached 15 to 18 km. from the summit, reaching parts of Camalig, Guinobatan, and Ligao City. "This effusive eruption continues up to now. There are lava flows, rock falls, and at times, collapse-generated PDCs," Bacolcol said.

For the past 24 hours, Phivolcs recorded five volcanic earthquakes, 400 rockfalls, and four PDCs. Bacolcol noted that the activity last Saturday, although not explosive, is still among the most dangerous volcanic hazards as PDCs are very hot and could incinerate anything in their path.

He also clarified that Phivolcs is monitoring other parameters prior to raising the volcano's alert level, and these include sustained lava fountaining, frequent eruptions, and big change in sulfur dioxide emissions.