Alert Level 3, according to resident volcanologist Ed Laguerta, means "there is an increased tendency toward an eruption with magmatic outburst possibly within the coming weeks."
The Philippine Institute of Volcanology and Seismology’s observatory at Lignon Hill recorded 31 low-frequency and two high-frequency quakes. A sulfur emission of 7,583 tons per day was recorded, way above the normal 500 tons per day.
Phivolcs raised Alert Level 2 at Mayon a few weeks ago after a lava dome was discovered at the crater.
Earlier, Phivolcs director Raymundo Punongbayan said Mayon spewed only 30 to 40 million cubic meters of volcanic debris when it last erupted on Feb. 24 last year, compared to 70 to 90 million cubic meters during its normal eruptions.
At least 14 of its major eruptions took place in the month of February, at which time the gravitational pull is greater because the earth and moon are closer to each other, according to meteorologist Othelo Estareja. — Celso Amo and Cet Dematera