Lava dome of Mayon Volcano collapses, says Phivolcs

LEGAZPI CITY, Albay — Government volcanologists said the lava dome in the crater of Mayon Volcano collapsed at about 1:47 p.m. Monday, causing a small pyroclastic flow to cascade some 1,480 meters down the Bonga Gully and producing a thin ash cloud which drifted east toward Tabaco City.

The Philippine Institute of Volcanology and Seismology (Phivolcs) attributed the partial collapse of the lava dome, which was discovered last March 19, to the steady accumulation of magma at the crater, which is about 150 to 200 meters in diameter.

"This is a normal occurrence at Mayon because of its conical shape, when magma intrudes into the crater," said volcanologist Alex Baloloy.

Baloloy said volcanologists are more concerned if there is a continuous increase in low-frequency volcanic tremors which indicates the presence of gaseous magma and could trigger a hazardous eruption.

During the past 24-hour observation period, 103 rockfalls and small lava avalanches as well as six low-frequency volcanic earthquakes related to magma ascent were recorded.

"Low-frequency earthquakes indicate slow ascent of magma through relatively open channels toward the surface," Phivolcs said in its latest bulletin.

In the past few days, Phivolcs noted an increase in Mayon’s overall unrest because of more frequent and more voluminous rockfalls, and more high-frequency, short-duration harmonic tremors.

"At present, the seismicity level is still fairly low due to the sluggish ascent of magma toward the crater," the institute added.

Meanwhile, Col. Dante Bonifacio, head of Task Force Mayon, said Army trucks are on standby in 17 designated pick-up points after the Provincial Public Safety and Emergency Management Office ordered some 17,155 villagers living on the slopes of Mayon to get ready for an evacuation anytime.

Bonifacio said 59 officers and 622 enlisted personnel have been on a 24-hour watch since January in Barangays Buhian, Magapo and Buang in Tabaco City; Calbayog in Malilipot town; Miisi in Daraga; Baligang in Ligao City; Anoloing, Upper Quirangay, Upper Cabangan and Upper Sua in Camalig. — With Felix de los Santos