By Celso Amo
LEGAZPI CITY --- About 2,289 families or 9,284 persons from the 6-kilometer permanent danger zone who are still staying in 12 evacuation centers from the towns of Camalig, Guinobatan, Malilipot and Tabaco City were sent home after the Philippine Institute of Volcanology and Seismology (Phivolcs) lowered the present Alert Level 3 to 2 Holy Thursday morning.
Renato Solidum, Department of Science and Technology(DOST) Undersecretary and Philippine Institute of Volcanology(Phivolcs) director, said the downgrading of present Alert Level 3 to 2 means the critical parameters of Mayon Volcano have shown a general drop from the trend.
“But this doesn’t mean there’s no more abnormality because the volcano is still inflated compared to previous baseline survey but the past observation that it has been inflated also showed a downward trend,” Solidum explained.
He said lava flows from the crater which was observed since March 18 and the number of earthquakes had registered to zero.
“This shows that the general feature of Mayon Volcano has a lesser degree of abnormality.”
Phivolcs lowered Mayon Volcano’s status from Alert Level 3 (decreased tendency towards hazardous eruption) to Alert Level 2 (moderate level of unrest) after its monitoring network and active observation of day-to-day conditions recorded a general decline in unrest.
For the past two weeks, seismic activity has waned from a peak of eighty-two to less than ten rockfall events attributed to the collapse of unstable lava flow deposits on the Miisi, Bonga and Basud drainage systems.
Low frequency earthquakes associated with magma degassing and short ash plumes were last recorded on March 15, 2018, although lava flow effusion from the crater could be detected until March 18, 2018.
The overall decline in seismicity indicates that there is currently no active transport of eruptible magma to the shallow levels of the edifice.
Since February 20, 2018, medium-term deflation of Mayon’s edifice has been recorded by electronic tilt and Precise Leveling (PL) surveys despite short-term episodes of inflation of its lower and middle slopes.
The downtrend in ground deformation follows a period of continuous inflation that began in October-November 2017 and implies that magma recharge from deep to shallower levels of the edifice has decreased.
Based on medium-term PL data, nonetheless, the volcano is still inflated relative to January 2010 baselines, most likely due to the presence of remnant magma beneath the edifice.
Magmatic sulfur dioxide or SO2 flux measured for the past two weeks has fluctuated within the range of 500-2000 tons a day which is lower than 700-4500 tons a day for the period of eruption from January 13, 2018 to March 8, 2018.
No new lava has been detected on Mayon’s summit crater by March 18, 2018.
The decline in observable surface parameters as above shown is consistent with the cessation of magma supply to the shallow levels of the volcanic edifice.
However, the lowering of the alert status should not be interpreted to mean that the volcano’s unrest has ceased, considering that the edifice is still inflated relative to its baseline level, Phivolcs officials warned.
Cedric Daep, Albay provincial security and emergency management office (APSEMO) chief, said full decampment of all Mayon evacuees has now been achieved.
“This is just timely since all evacuees want to observe Holy Week with their families in their homes,” Daep said adding that all issued Mayon advisories are now lifted.
Tourists were allowed to observe their pilgrimage during Lent to the Mayon Resthouse in Barangay Buang in Tabaco City and ATV operators can now resume their operation.
“But mountain climbing to the crater and going to the lava front are still prohibited due to the threat of rock falls,” Daep said.
He warned that said those who bring visitors and tourists to risky and dangerous areas will be responsible.