Phivolcs: Mayon eruptions will last 2-3 months more
LEGAZPI CITY, Albay — State volcanologists said yesterday that the restive Mayon Volcano will continue to exhibit small eruptions and lava fountaining or even a major blast and pyroclastic flow for the next 2-3 months, at least.
Ed Laguerta, Philippine Institute of Volcanology and Seismology (Phivolcs) resident volcanologist who is based here, said they are still assessing Mayon’s volume of eruptible magma and explained that based on historical accounts, its eruptions would last 2-3 months or even up to four months.
Based on the data being assessed by Phivolcs, Laguerta described two possible scenarios for Mayon – one, a continued oozing out of lava with small eruptions in between or two, a major blast and pyroclastic flow,
which is a deadly combination of hot lava blocks, pumice, ash, and volcanic gas.
At present, Mayon is exhibiting scenario one, which is the continued lava fountaining that may last for three more months, he said.
“Scenario 1, Mayon will continue its lava fountaining and quite extrusion of lava flow into the Miisi gully and Bonga gullies. The present activities could be similar to 1993 eruption. The current conditions with no measurable indication of changes as of the present and Mayon will be maintained to alert level 4,” explained Laguerta.
What is feared is scenario two, which is a progression of Mayon into an explosive eruption that would spew out hot lava blocks, pumice, ash and volcanic gas that may glide down the slope and devastate residential areas in the villages surrounding the volcano.
In explaining scenario two, Laguerta said: “If lava degasses sufficiently to plug the vent and over-pressurize the volcanic conduit or magma ascent rates drastically increase, this and a explosive eruption could become imminent; scenario 2 is similar to the 2000 to 2001, 1984 and 1968 eruption; Lava flow phase followed by explosive eruption phase, and from this, alert level 5 will be raised.”
However, the seasoned volcanologist said the probability of scenario two has the lower probability as of now.
He said Phivolcs is still considering the volume of eruptible magma with an approximate 50 million cubic meters based on the estimate of eruptible magma from the magma supply rate per year.
When asked about the probability of scenario two happening in terms of percentage, Laguerta told The Manila Bulletin: “Mahirap sabihin kung ilang porsyento. Mag-a-assume kayo niyan (It’s difficult to gauge the probability by percentage. You would be guessing). But the higher probability is scenario 1, which is happening now.”
He added that if scenario one will prevail, Mayon’s restiveness may take longer. “Kung pakonti-konti ang inilalabas ni Mayon, yung lang, matagal tayo dito. Matagal tayong magsasama-sama nito (If Mayon keeps on emitting in small amounts, we’re here together for the long haul),” he said.
Latest events
Another round of lava fountaining, lava flow and degassing characterized the volcano’s activity within the past 24 hours.
Phivolcs said Mayon belched out lava twice last Sunday producing 500-meter and 550-meter high ash plumes at 10:38 a.m. and 1:52 p.m., respectively.
The first of the two events saw sporadic lava flows that lasted about an hour and 54 minutes.
The events were accompanied by booming sounds, which was heard 10 kilometers from the volcano.
Throughout Sunday evening, Phivolcs said quiet lava effusion fed lava flows in the Miisi and Bonga-Buyuan channels and barrancos between these with the exception of two weak lava fountaining events at 2:54 a.m. and 5:22 a.m. Monday.
It pointed out that these were visually observed, ejecting high volumes of incandescent lava that have advanced to 3.2 kilometers and 4.5 kilometers, through the Miisi and Bonga-Buyuan channels respectively, from the volcano summit.
Phivolcs recorded a total of 164 volcanic earthquakes, most of which corresponded to sporadic and weak fountaining events, two rockfalls, and one tremor within a 24-hour monitoring period. (With reports from Ellalyn B. de Vera and Aaron B. Recuenco)