By Celso Amo
LEGAZPI CITY --- Three incidents of rock fall were observed at Mayon Volcano during the past 24 hours.
Ed Laguerta, Mayon resident volcanologist of the Philippine Institute of Volcanology and Seismology (Phivolcs) based at Ligñon Hill Observatory, said there were observed occurrences of rock fall at the upper slopes of the volcano which could either be old or new.
“If these are from old lava deposits, they could have been loosened volcanic materials affected by rainfall,” said Laguerta in a text message Friday morning.
He also said that another scenario is that the restive volcano could move on to an abnormal condition from a quiet eruption due to portions of the lava dome at the summit of Mayon that could have been pushed outside by an ascending magma from a deeper source.
“For example, there were rock fall occurrences before the start of an eruption in the month of January this year.”
Alert Level 2 currently prevails over Mayon Volcano which means the volcano is still at moderate level of unrest.
Laguerta admitted that there are still small explosions occurring at Mayon volcano, since the prolonged milder eruptions in the early months of this year mellowed on this third month of March.
The state weather bureau said that as of 4:00 a.m. Friday, the center of tropical depression Domeng was estimated at 470 km east of Casiguran, Aurora with maximum sustained winds of 60 kilometer per hour near the center and gustiness of up to 75 kph.
“The current level of rainfall over the volcano cannot yet trigger lahar flow,” Laguerta added.
Degassing at the active vents could not be observed due to thick clouds covering the summit.
Crater glow could not be observed due to thick clouds covering the summit during the night.
Meanwhile, sulfur dioxide emission was measured at an average of 1,160 tonnes a day on 27 May 2018.
Precise leveling data obtained April 14, this year, indicate inflation of the edifice relative to March 22-29 dta, while electronic tilt data show sudden slight inflation of the mid-slopes beginning May 5, 2018.
Medium-term ground deformation data, however, show that the edifice is still deflating consistent with the decline in unrest but is still inflated relative to 2010 baselines.
Phivolcs reminds the public to refrain from going up the mountain because of sudden explosions when rainwater comes into contact with old lava deposits as well as lava collapse, pyroclastic density currents or PDCs, and ashfall can still occur and threaten areas in the upper to middle slopes of Mayon.
Entry into the 6-km radius permanent danger zone and the extended 7-km radius danger zone in the south-southwest to east-northeast sector from Anoling, Camalig town to Sta. Misericordia in Sto. Domingo town is strictly prohibited, Phivolcs warned.