Mt. Mayon in Legazpi City, Albay province. (PNA file photo by Connie Calipay)
LEGAZPI CITY -- Mt. Mayon here has again displayed signs of restlessness, the Philippine Institute of Volcanology and Seismology (Phivolcs) said on Tuesday.
Phivolcs instruments at the Lignon Observatory recorded 16 volcanic earthquakes, six rockfall events, above normal gas emission and bulging at the volcano’s edifice for the past 24 hours.
In an interview, Eduardo Laguerta, Phivolcs resident volcanologist here, described the tremors as “low frequency”, a movement triggered by magma build-up and gas pressure.
“Low-frequency quakes are usually triggered when magma is developed and intrude inside the volcano’s vent,” he explained.
Laguerta said the quakes show that the volcano is starting to “resupply” or is preparing for an upcoming eruptive event. “This is normal every time that Mayon wanted to show its restless behavior,” he noted.
He also said the dome at the volcano’s crater could be growing because of magma build-up and gas.
Laguerta said these abnormalities are still being closely monitored and there is no cause for alarm that the volcano could have another major eruption anytime soon.
Asked if the volcano’s restiveness would be a ground for raising Mayon Volcano's alert status, he said this would depend on the abnormalities it would exhibit in the next few days and weeks.
The parameters for raising the alert status include high and low-frequency earthquakes, gas emissions, inflation at the edifice, crater glow and lava trickles at the volcano’s summit.
Laguerta said sulfur dioxide emission was measured at 680 tonnes a day, a bit higher from the normal level of 500 tonnes a day.
A slight bulging at the volcano’s edifice continued to be observed by the agency’s Precise Leveling instrument.
Alert Level 2 (moderate level of unrest) remains hoisted over Mayon.
Phivolcs warned the public to keep out of the 6-kilometer permanent danger zone (PDZ), as well as the precautionary 7-km Extended Danger Zone as sudden explosions, lava collapses, pyroclastic density (PDCs) and ash fall could still occur and threaten areas in the upper to middle slopes.
Active stream/river channels and those identified as perennially lahar-prone areas on all sectors of the volcano should also be avoided especially during extreme weather conditions when there is heavy and prolonged rainfall.
Laguerta said civil aviation authorities must advise pilots to avoid flying close to the volcano’s summit as airborne ash and ballistic fragments from sudden explosions and PDCs may pose hazards to aircraft. (PNA)