Government volcanologists raised yesterday the alert level at Mayon Volcano in Albay from "alarming" to "critical" following signs that hot molten rock was slowly but steadily rising to the crater.
The Philippine Institute of Volcanology and Seismology (Phivolcs) said Alert Level 3 means that "fresh magma (hot molten rock) is close to the crater," but noted that an eruption "is likely only if the present trend of relatively high volcanic unrest is sustained."
Phivolcs said a lava pile on the summit of Mayon Volcano has been observed since Feb. 12, accompanied by an increase in sulfur dioxide emissions and volcanic earthquakes.
"The observations consistently and strongly suggest that slow but active lava ascent is taking place beneath the crater," Phivolcs said in a statement.
The institute said continued lava ascent would cause the lava pile to overflow, possibly triggering "rockfalls with or without ash puffs and explosions, lava flows or pyroclastic flows."
Initial volcanic activity, Phivolcs said, "will most likely affect the southwestern and eastern sectors."
With the alert level up, disaster control officials in Legazpi City ordered yesterday the total evacuation of villagers inside the six-kilometer radius permanent danger zone around Mayon.
Bert Realuyo, deputy chief of the provincial disaster coordinating council, said only three of the five barangays within the danger zone are still inhabited. These are Anoling in Camalig town, Calbayog in Malilipot, and Magapo in Tabaco.
Realuyo said residents of Barangays Miisi in Daraga and Baligang in Ligao have been evacuated.
Volcanologist Ed Laguerta advised residents near the Bunga and Basud gulleys in Legazpi City and Sto. Domingo town, respectively, to be on alert against rockfalls.
Phivolcs has been monitoring Mayon since last May. In June, it raised Alert Level 2 at the volcano after it belched thick clouds of smoke and ash. Since then, four other smoke and ash outbursts have been recorded, the last of which was on Jan. 5 this year.
The 2,462-meter-high Mayon is famous among local and foreign tourists for its perfectly symmetrical cone.
Mayon's last major eruption was in February 1993, when 70 people were killed and more than 50,000 people were evacuated.
Its deadliest eruption was in 1911 when it buried the entire town of Daraga under ash and killed more than 1,300 people. - With wire reports