Volcanologists at the Philippine Institute on Volcanology and Seismology (PHIVOLCS) mull over raising the highest possible alert status on Mount Mayon in Legazpi, Albay after observing continuing trends of increasing volcanic activities in the volcano.

Jimmy Sincioco, spokesperson of PHIVOLCS on Mount Mayon activities, said that hoisting Alert Level 5 would be probable in the next few days as soon as they observed “surface manifestations” hazardous eruption in the perfect-coned volcano.

“Even if there have been intensified level of volcanic activities in Mayon, we are still waiting for some critical factors before we raise the status to Level 5,” Sincioco said, explaining that Level 5 is only hoisted if there is already hazardous eruption going on.

“But right now, there are still no surface manifestations like voluminous eruption columns that could cause hazardous pyroclastic flows and perceptible earthquakes,” he reiterated in a phone interview.

Sincioco clarified that the pyroclastic flow presently coming down from the higher and middle slopes of Mayon can only be considered as secondary, which originates from the piles of lava deposit earlier spewed by the world-renowned volcano.

The spokesperson explained that the raising of Alert Level 5 requirse pyroclastic materials to be spewed by explosive eruption called as “voluminous ash explosion columns.”

When loud explosions are heard and when earthquakes near Mount Mayon become actually felt by residents in Legazpi, Albay province, Sincioco noted that would be the right time to raise Alert Level 5.

Since Sunday, seismic network of PHIVOLCS recorded activities that remain “elevated in number and size” with a total of 1,266 volcanic earthquakes at maximum deflection after a 24-hour observation period.

“Even though we have recorded earthquakes and harmonic tremors, these were only detected by seismographs. We have yet to feel it,” he explained.

PHIVOLCS added that Sulfur dioxide (SO2) emission rate remained very high and was measured at an average of 6,529 tons per day yesterday, but thick clouds covering upper and middle slopes of Mayon hamper its visual observation.

However, an intensified crater glow was observed during a short cloud break Sunday with audible booming and rumbling sounds were still intermittently heard for the past 24 hours.

Sincioco emphized that red hot lava has continuously flowed down along the Bonga-Buyuan, Miisi and Lidong gullies, 5 kilometers downslope from the summit along the Bonga-Buyuan gully.

On Sunday, PHIVOLCS raised Alert Level 4 or the status of imminent hazardous eruption after Mayon indicated “intense unrest” marked by persistent tremor and many low-frequency-type earthquakes.

Last raised in 2006, Alert Level 4 is hoisted when Sulfur dioxide emission level shows sustained increase of abrupt decrease while incandescent lava fragment reaches the summit area of the volcano, resulting to an intensified crater glow.

“What makes this situation different from 2006 is the presence of lava fountain in Mayon’s crater that suggest rich dust content. It makes raising Alert Level 5 more probable,” he said.

Sincioco said that Alert Level Status 4 was raised in Mayon volcano in 2000 and 2001.