The Philippine Institute for Volcanology and Seismology (Phivolcs) said although Mayon Volcano did not show any activity during the past 24-hour observation period, a hazardous eruption is still possible within weeks.
Mayon’s sulfur gas emission dropped to 138 tons on Saturday, way below the reading last Thursday at 308 tons per day.
Although the volcano’s alert status remains at Alert Level 3, the local government of Albay said they are prepared in case Phivolcs raises Mayon’s alert level to 4.
“Albay is ready for 4. You just can’t take chances on the lives of people. Kung hindi pumutok o sumabog, eh di mabuti – no regrets. Eh kung sumabog naman, no casualty,” Albay governor Joey Salceda said in a Facebook post as quoted by GMA News.
Under alert level 4, the volcano will exhibit intense unrest with persistent tremors and low-frequency quakes. Sulfur dioxide emission may also show sustained increase or abrupt decrease while the crater glow is intense with incandescent lava dome, lava fountain and lava flow in the summit area.
Phivolcs is closely monitoring the situation, particularly the inflation of the volcano’s lava dome and its emission of sulfur dioxide.
Phivolcs resident volcanologist Ed Laguerta described Mayon’s current state as the “lull before the eruption.” “Ibig sabihin nito ang ibang gas hindi nakakalabas, so nakakadagdag ito uli sa pag-pressurize uli, ‘yung pag-iipon ng lakas sa loob ng bulkan,” Laguerta said in an interview with DZMM radio.
“Kaya sa ngayon medyo delikado pa po ang kalagayan ng bulkan,” he added.
Phivolcs science research specialist Eduardo Villacorte said in a Philstar.com report that pressure build-up has increased somewhere along the column due to a clogged magma conduit, preventing the ascent of new magma towards the vent and the lava dome at the crater surface. He could not say until when the magma column would be able to hold the amount of pressure inside.
Villacorte said factors determining the explosive potentials of magma are viscosity, water content and crystals, considering that the magma at Mayon is andesitic.
Phivolcs also noted worsening abnormal condition of the volcano, like the continuous ground deformation with an inflation of three millimeters in 10 days. Ground swelling also appeared on both the northern and southern parts of the volcano because the magma is passing through one channel and its force is even.
According to Cedric Daep, director of Albay Public Safety and Management Office, the local government is preparing for three scenarios in case of Mayon’s eruption.
First is the sectoral collapse of the south east lava dome that can affect the municipalities of Daraga, Sto. Domingo and Legaspi City. The second scenario is the collapse of the north side lava dome. Daep explained that the third and worst scenario is the explosion of a massive ash column that can be dangerous to towns surrounding the volcano.
The Provincial Disaster Risk Reduction and Management Council recommended that the 6-kilometer radius permanent danger zone around the volcano and the 7-kilometer extended danger zone (EDZ) on the southeastern flank be enforced due to the danger of rock falls, landslides and sudden explosions or dome collapse that may generate hazardous volcanic flows.
More than 12,000 families or 55,000 people residing within the volcano’s danger zone had been evacuated to makeshift evacuation centers, usually schools and other government buildings. More than 10,000 farm animals, 6,000 pet dogs and other animals were also moved to safety.
Mayon started showing renewed volcanic activities last August 14.
The volcano’s most destructive eruption occurred in February 1814 that killed 1,200 people and destroyed Cagsawa church.