MANILA (UPDATED)— Mayon Volcano's status has been raised to Alert Level 3, the state seismology office Phivolcs said on Thursday, warning that there is now an "increased tendency towards a hazardous eruption."

Phivolcs reported that "very slow extrusion of shallow degassed magma is ongoing and is incrementally increasing in rate; i.e., effusive magmatic eruption is taking place."

"This means that Mayon is exhibiting magmatic eruption of a summit lava dome, with increased chances of lava flows and hazardous PDCs [pyroclastic density current] affecting the upper to middle slopes of the volcano and of potential explosive activity within weeks or even days," it added.

The raising of Mayon's status came just days after Phivolcs hoisted Alert Level 2 for the Albay volcano, citing the increase in rockfall from the volcano's summit lava dome.

• Mayon Volcano rockfall activity doubles in 24 hours
• Mayon Volcano status raised to Alert Level 2

EVACUATION, ASHFALL

Phivolcs ordered the evacuation of the 6-kilometer radius permanent danger zone due to the danger of PDCs, lava flows, rockfalls, and other volcanic hazards.

"Increased vigilance against pyroclastic density currents, lahars, and sediment-laden streamflows along channels draining the edifice is also advised," it said.

Flying close to the volcano’s summit is prohibited, Phivolcs said, "as ash from any sudden eruption can be hazardous to aircraft."

It also warned that ashfall events could occur on the south side of the volcano.

• Flights barred near Taal, Mayon due to increased activity: CAAP

LETHAL

Pyroclastic density current or PDC from Mayon can reach between 500 to 900 degrees Celsius with a speed ranging anywhere from 30 to 700 kilometers per hour, said Phivolcs Chief Science Research Specialist Maria Antonia Bornas.

A PDC is composed of hot ashes, shattered lava and hot volcanic gasses, and other debris along its path that rapidly flow from the volcano’s crater.

“Bakit siya lethal? Kasi mainit ito. Nakakapagdulot siya ng pagsunog. Lahat ng pwedeng madaanan nito kahit yung dilute cloud lang, mainit pa rin yan at ito ay may dalang maraming mainit na abo. Kaya pag nalanghap natin yung cloud na ‘yun, kahit madaplisan lang, pwede tayong mamatay," Bornas said.

She added that Phivolcs is closely monitoring Mayon’s activity, particularly any increase in certain parameters, as well as the level of sulfur dioxide to be able to determine any explosive activities.

“Ang explosivity ng isang eruption ay dahil sa volcanic gas. both dahil ito ang nagdadala ng pressure ng magma at pag ito ay naiipit sa loob ng bulkan ay sigisigi itong nadagdagan," Bornas said.

“Habang umaakyat kasi ang magma, kumakawala ang volcanic gas sa kaniya. so kung nakukulong ang magma ay napepressurize ang systema. Siya na nga ang nagdadala ng pressure nkakapag induce pa siya ng pressure,” she said.

— with a report from Raphael Bosano, ABS-CBN News