LEGAZPI CITY, Albay: Mayon Volcano recorded a ground swelling of three millimeters during the past 10 days based on the latest ground deformation survey of the Philippine Institute of Volcanology and Seismology (Phivolcs) geodetic team.
Phivolcs resident volcanologist Ed Laguerta on Thursday said that although the volcano appears to be calm and there have been less earthquakes and rockfall events in the almost one-week period, their instruments have recorded a continuous inflation of the ground and an increase in the volume of sulfur dioxide (SO2) emission.
Laguerta said this means that magma is continuously rising towards the crater.
“For 10 days now, we uncovered the inflation of Mayon increased by 3 milimeters. We’re looking thoroughly with this kind of precursor which is new behavior exhibited by Mayon,” Laguerta said.
He said that since 2013, only 10mm sustained surface inflation but after the lava trickles it decreased by .65 mm which is an indication of very significant and possible prelude of explosive explosion.
“We’re looking at this scenario as prelude to a big explosion after 1984. This is a very significant increase while the S02 measurement dropped significantly that is very dangerous,” Laguerta said.
He added that if a strong force occurs in the Mayon Volcano due to heavy rains in the area and water enters the magma chamber, this could trigger small eruptions that could in turn cause a magmatic eruption.
“This is what we call a phreatic explosion,” said Laguerta, who also noted that steam emission now is few, which, he explained, is due to the sealed crater of the volcano.
Mayon last erupted in May 7, 2013 where four foreign hikers and a Filipino tour guide were instantly killed by cascading hot volcanic materials.
Since 1616, the deadliest eruption recorded was the 1814 occurrence that killed 1,200 people and in 1987 where the entire town of Sto. Domingo was hit and burned by cascading pyroclastic materials locally called here as “pangiritikiti”
For almost three weeks since Phivolcs raised Mayon’s alert level to 3, the seismic network recorded three rockfall events during the past 24-hour observation period.
Ground deformation data showed no significant change from August based on last month’s precise leveling survey although the edifice remains inflated compared to baseline measurements. Tilt data also indicate continuous inflation at the base of the edifice since August. The data indicate that the volcano is still in a state of unrest due to the movement of potentially eruptible magma.
Authorities strictly prohibit entry within the six-kilometer-radius permanent danger zone and extended 7 to 8-km danger zone at the southeast portion of the volcano.
PNA WITH RHAYDZ BARCIA