Philippine Institute of Volcanology and Seismology (PHIVOLCS) Director Teresito Bacolcol said on Tuesday that an effusive eruption is being observed at Mayon Volcano and that the agency is not ruling out raising the Alert Level from 3 to 4.

Mayon Volcano is currently at Alert Level 3, characterized by a moderate level of unrest. Effusive eruption, Bacolcol explained, is the slow release of volcanic materials from the volcano’s edifice.

When the Alert Level is raised to 4, PHIVOLCS will be expanding the danger zone, he reassured.

“Kapag i-raise na natin ‘yung alert level from Alert Level 3 to Alert Level 4, we may expand the danger zone. So pag nakakita tayo ng sustained increase or decrease ng sulfur dioxide, kapag nagkaroon tayo ng longer lava flows, nagkaroon ng frequent pyroclastic currents, and curtain lava fountaining, kapag tumataas din ‘yung volcanic earthquakes natin, kapag ‘yung edifice ng bulkan ay nagi-inflate, and kapag may minor explosions, we will raise it to Alert Level 4,” Bacolcol said in an exclusive interview on Balansyado.

He clarified that not all signs have to be present, but most of them.

The agency has also noted dome building or dome growth occurring on the volcano, which is a mound of sticky lava that piles up at the crater instead of flowing downhill, he added.

“Mayroon tayong bagong lava coming out and nagpa-pile up and nagdadagdag at the top of the volcano. Even if it’s slow and not explosive, that is still an eruptive process,” said Bacolcol.

The PHIVOLCS director also warned that rain could wash down volcanic deposits from the slopes, triggering lahars, especially during prolonged or heavy rainfall.

“May mga deposits tayo na puwedeng ma-remobilize ang lahars, lalo na’t kapag may continuous and torrential rains also. So ‘yun ‘yung paalala natin sa ating mga kababayan lalo na ‘yung nakatira malapit sa riverbanks na mag-ingat and remain vigilant. And kapag tuloy-tuloy ang malakas na pag-ulan, then they have to move to a higher place or transfer to a safer area,” he said.

While an explosive eruption remains possible, PHIVOLCS expects the effusive eruption to continue, similar to what occurred in 2023.

Meanwhile, ash emission activity was recorded at Mt. Kanlaon in Negros Island from 5:55 a.m. to 9:25 a.m., lasting about three hours and 30 minutes.

The volcano remains under Alert Level 2, with an ash plume reaching around 800 meters high. One volcanic earthquake was recorded on Monday, while sulfur dioxide emissions were measured at 1,284 tons per day.