2023 June 21
MANILA – Raising Mayon Volcano’s alert status from Level 3 (increased tendency towards hazardous eruption) to Level 4 is unlikely for now, the chief of the Philippine Institute of Volcanology and Seismology (Phivolcs) said Wednesday.
In a public briefing, Phivolcs officer in charge Teresito Bacolcol said they are considering several parameters before increasing a volcano’s alert level.
“Kapag dumadami po iyong earthquake na naitala natin, kapag nagkakaroon na po ng lava fountaining, dumadami iyong rock fall events natin, dumadami iyong pyroclastic density current events, iyon po ang mga indikasyon na itataas natin to Alert Level 4. Pero so far, hindi pa po natin nakikita iyan ngayon (If we record an increase in earthquakes; when there’s lava fountaining; increased rockfall events, pyroclastic density current — these are indications that we need to increase Mayon’s alert level to Level 4. We don’t see these indicators so far),” he said.
Another parameter he cited is an increase in sulfur dioxide emission. “Yesterday, we recorded 389 tonnes of sulfur dioxide, which is low compared to the average 500 tonnes per day that the volcano usually emits,” he said.
Alert Level 4 means a hazardous explosive eruption is possible within hours to days.
Under Alert Level 3, on the other hand, Mayon is exhibiting magmatic eruption of a summit lava dome, with increased chances of lava flows and hazardous pyroclastic density currents (PDCs) affecting the upper to middle slopes of the volcano and of potential explosive activity within weeks or days.
Bacolcol said Mayon Volcano continues to exhibit effusive eruption, which means magma is slowly released. The lava flow reaches 2.5 km. away from the crater, along the Mi-isi gully, and 1.8 km. along the Bonga gully.
“The debris brought about by rockfalls and PDCs have reached 3.3 km. from the crater,” he added.
Bacolcol noted that only seven PDCs, 299 rockfall events, and two volcanic earthquakes were recorded at the Mayon Volcano from Tuesday to 5 a.m. Wednesday.
He said these parameters are similar to what the Mayon Volcano was exhibiting in 2014. “We hope that this (trend in) parameters will not change, so the eruption will just be effusive,” he said.
The Phivolcs chief also said that extending the 6-kilometer (km) permanent danger zone (PDZ) to seven-km. is unlikely at this time. This is because lava flows slowly, around 350 meters towards the steep slope, per day, Bacolcol explained.
“We don’t see an indication that we need to extend the PDZ,” he said.
Ma. Cristina Arayata (PNA)