MANILA, Philippines - The Philippine Institute of Volcanology and Seismology (Phivolcs) continued to monitor the decrease in volcanic quakes and rock fall in Mayon volcano in Albay for the past 24 hours, and officials are now considering the possibility of lowering the alert level from 4 to 3.
Volcanologists, however, are still not ruling out the possibility of a violent eruption in the next few days.
Albay Gov. Joey Salceda said the Provincial Disaster Coordinating Council (PDCC) and the Phivolcs are studying the possibility of lowering the alert status of Mayon, but added the agency needs a few more days of observation.
In an interview with radio dzBB, Salceda said that there is a 60 percent possibility that the alert status of Mayon will be lowered in the next three to four days.
Salceda heaved a sigh of relief over the development.
“I am quite relieved about the possibility of a lower alert level,” he said.
Phivolcs director Renato Solidum said that if the alert level is lowered from 4 to 3, the possibility of a hazardous explosion is lower.
“If no significant events occur during the next few days, Phivolcs shall consider lowering the alert level from 4 to 3,” Solidum said in a text message to The STAR.
In its latest advisory, Phivolcs said the seismic monitoring network around the volcano detected 28 volcanic earthquakes, down from 60 quakes the other day.
A total of 91 rock fall events - related to the detachment of lava fragments at the volcano’s upper slopes - were observed during the past 24 hours, from 267 rock fall events on Thursday.
No ash explosion was observed during the period.
It said weak to moderate emission of white steam at the summit crater was seen during a cloud break.
Phivolcs said flowing lava and intermittent rolling incandescent lava fragments were observed Thursday night.
Sulfur dioxide (SO2) emission rate had increased from 1,158 tons the other day to 1,255 yesterday.
Volcano’s slope healing
After 18 days of spewing lava and other volcanic materials, the crater and slope of Mayon have started to heal after four days of calmer volcanic activity.
“If Mayon volcano will no longer proceed to an explosive-eruption phase, we can say that it has almost completed already its self-rebuilding ability. We can see that its fractured crater facing Legazpi City as well as the deep and long cracks on its slope are already patched up by lava materials,” senior volcanologist July Sabit told The STAR.
Sabit said that the continuous flow of small volume of lava could complete the volcano’s healing process until all its fissures and damaged surface caused by previous eruptions are fully restored.
Alex Baloloy of Phivolcs said that the 1984 explosive eruption caused a portion of the crater rim in the southeast quadrant to collapse, while the 1993 and 2000 equally strong eruption intervals further ripped the volcano’s mouth, and the heavy rainfall from super typhoon “Reming” scoured the gullies.
“But this 18-day lava flow filled these cracks, gullies, and even restored the damaged crater,” Baloloy said.
Filled by lava materials were the estimated 140-meter deep, 200-meter wide and four-kilometer scar known now as the Bonga gully and the Bonga-Buyuan channel, both in the Legazpi City side; and the Miisi-Lidong channel in Legazpi and Sto. Domingo town portion.
Ed Laguerta, Phivolcs resident volcanologist in Legazpi City, said the ejected volcanic material is estimated to have reached 20 million to 23 million cubic meters already. Mayon ejected 50 million to 60 million cubic meters of rocks and volcanic debris during its past eruptions.
Laguerta said that should the volcano finally stop its rumbling, the latest lava flows could fully restore its near-perfect symmetry once lava materials cool off and turn into molten or solid-rock portions of the slope.
“These lava fragments become solid rock once they finally cool off. But it takes months before they solidify and form part of the volcano surface,” Laguerta explained, adding that Mayon’s self healing ability earns her the title “Majestic Mayon.”
Mayon volcano has an estimated base-diameter of 20 kilometers and height of 2,462-meters above sea level, and has erupted at least 50 times since 1616. With Cet Dematera