Philippine Institute of Volcanology and Seismology (Phivolcs) Officer-in-Charge (OIC) Teresito Bacolcol is not discounting the possibility that lava flows caused by the ongoing “effusive eruption” of Mayon Volcano may breach the six-kilometer permanent danger zone.
“So far 2.5 kilometers from the crater [ang lava flow] and kapag tuloy-tuloy po ‘yun, pwedeng ma-breach yung six-kilometer permanent danger zone (Right now, the lava flow has reached 2.5 kilometers from the crater. If it continues, the six-kilometer permanent danger zone could be breached),” Bacolcol said in a televised public briefing on Wednesday, June 21.
However, the Phivolcs OIC hopes that because the lava is still moving slowly at this point, it will not go beyond the permanent danger zone.
“Masyadong mabagal [ang lava flow]. Mga 350 meters per day lamang. Hindi na siya makausad minsan [kaya] ‘yung lava front nagiging rockfall (The lava flow is very slow. It is moving only about 350 meters per day. Sometimes it cannot move forward so the lava front turns into a rockfall),” he said.
According to Bacolcol, there is still no indication that the danger zone should be expanded to seven kilometers.
Molten lava glows as it flows from the mouth of Mayon Volcano in this photo taken from Barangay Budiao in Daraga, Albay, on Saturday night, June 17, 2023 (Ali Vicoy/Manila Bulletin)
Volcanic quakes, pyroclastic density currents, rockfalls continue
Phivolcs said a “very slow” effusion of lava from the summit crater of Mayon Volcano continued to feed lava flows and collapse debris on the Mi-isi and Bonga gullies on the south and southeastern sides of the volcano, respectively.
“Patuloy pa rin itong nagpapakita ng effusive eruption meaning mayroon pa ring slow release of magma mula sa edifice ng bulkan (It continues to show an effusive eruption meaning that there is still a slow release of magma from the volcano’s edifice),” Bacolcol said.
Phivolcs defines effusive eruption as the outpouring of lava onto the ground, as opposed to explosive eruption, which is characterized by violent magma fragmentation.
Over the past 24 hours, lava flow was still at 2,500 meters and 1,800 meters long along the Mi-isi and Bonga gullies, respectively.
Meanwhile, collapsed debris has accumulated up to 3,300 meters away from the crater.
Phivolcs also recorded seven dome-collapse pyroclastic density currents (PDCs) that lasted three minutes, 299 rockfall events, and two volcanic earthquakes.
Similar to 2014 eruption
“‘Yung pinapakita niya ngayon ay nagre-reflect doon sa pinapakita noong 2014. From August 2014 to November 2014, nagkaroon ng lava flow and then huminto. So sana ganito yung ipapakita niya (What is happening in Mayon now reflects what happened in 2014. There was a lava flow from August 2014 to November 2014, and it gradually stopped. So I’m hoping that this will also what will happen now),” Bacolcol said.
“Sana hindi na magbabago yung mga parameters na nakikita natin. Para all throughout, effusive eruption lamang (I really hope that the parameters we are seeing stay the same. So it will just be an effusive eruption),” he added, noting that the 2014 event was a “relatively quiet eruption.”
Alert Level 3 stays
Bacolcol said Mayon Volcano’s alert level is still maintained.
Mayon Volcano has been on alert level 3 since June 8, indicating that a “hazardous eruption is possible within weeks or even days.”
It is "currently in a relatively high level of unrest as magma is at the crater,” Phivolcs pointed out.
The evacuation of residents within the six-kilometer permanent danger zone has been recommended due to the risk of PDCs, lava flows, rockfalls, and other volcanic hazards.
Phivolcs warned the public to be cautious of PDCs, lahars, and sediment-laden stream flows along channels draining the volcano edifice.
It pointed out that heavy rainfall could cause channel-confined lahars and sediment-laden stream flows on channels where PDC deposits were emplaced.
Likewise, it said that ash fall events may “most likely” occur on the south side of the volcano, based on the current wind pattern.
Phivolcs advised civil aviation authorities to ask pilots to avoid flying close to the volcano because ash from sudden eruption may pose hazards to aircraft.