Mayon explosive eruption looms; danger zone widened
The Philippine Institute of Volcanology and Seismology (Phivolcs) has warned disaster risk reduction and local government officials to brace for an explosive eruption of Mayon Volcano in the com- ing days.
Phivolcs’ warning came as Mayon spewed a huge column of ash at 12:45 p.m. last Monday, blanketing large areas on the west side of the volcano’s flank and causing zero visibility in some areas.
Ash fall carried by prevailing seasonal northeast wind reached as far as Nabua, Baao and Iriga in Camarines Sur, about 70 kilometers from the volcano, according to Department of Science and Technology undersecretary and Phivolcs director Rene Solidum.
Solidum said the cycle of explosion including lava fountaining had a more than fourhour interval, adding that at 8:54 a.m. yesterday, Mayon again spewed ash.
“You will observe that there are white and dark ash clouds accompanying the explosion – the same during last Monday when magma had mixed with water vapor that reached five kilometers above the summit, triggering a small pyroclastic flow with less volcanic debris at the Boyoan side,” said Solidum.
He said the lava fountaining episodes of Mayon showed Strombolian type of eruption, accompanied by whitish clouds.
“Our advisory to officials, now at Alert Level 4, (is that while we expect a stronger eruption we don’t expect a worst-case scenario),” said Solidum.
Solidum reminded residents affected by the eruption not to panic but to be vigilant of the health hazards of volcanic ash.
“The public is reminded to observe the danger zone, not to panic, but in essence just be ready,” Solidum said in an interview with CNN Philippines.
The danger zone was extended to eight kilometers from the volcano’s vent following yesterday's eruption.
He also urged the public to prepare gas masks, handkerchiefs or cloths to prevent inhalation of fine ash.
According to the Philippine Red Cross (PRC), exposure to falling ash may cause a number of health problems especially respiratory illnesses such as nose and throat irritation, coughing, bronchitis and discomfort while breathing.
It may also cause eye irritation and minor skin problems, said PRC.
At 12:43 p.m. last Monday, a dense, five-kilometer tall eruption column was generated by a short-lived phreatomagmatic eruption that lasted eight minutes based on the seismic record.
Volcanic ash was blown west and fell on Guinobatan, Camalig, Oas, Polangui and Iriga.
This was followed by a minor degassing event at 5:51 p.m. last Monday that generated a short 500 meter-high ash plume.
Between 9:37 p.m. last Monday and 5:25 a.m. yesterday five episodes of intense but sporadic lava fountaining from the summit crater lasting three to 30 minutes occurred.
The lava fountains reached 500 meters to 700 meters high and generated ash plumes that reached 2.5 kilometers to three kilometers above the crater.
The events fed lava flows on the Miisi and Bonga Gullies, sprayed near-vent lava spatter and fed incandescent rockfall on the summit area.
A total of two explosion-type earthquakes corresponding to the vertical column eruptions, 15 tremor events, some corresponding to lava fountaining episodes, 35 rockfall events and pyroclastic density currents from lava collapse were recorded by Mayon’s seismic monitoring network.
Ed Laguerta, Mayon resident volcanologist, said the cauliflower shape of the ash column last Monday was whitish but the ash column yesterday morning had smaller pyroclastic flow and denser.
“So from now on the volcanic debris thrown by the volcano can go anywhere,” said Laguerta during a press conference at Albay Public Safety and Emergency Management Office (APSEMO) yesterday morning.
APSEMO said the number of evacuees has swollen to 56,217. Of these, 3,718 families or 15,260 came from within the nine-kilometer radius of the crater of the volcano.