Mayon ‘overdue’ for eruption

MANILA, Philippines - Mayon Volcano’s activity intensified anew in the last 24 hours as a state volcanologist warned yesterday that it is “overdue” for a strong eruption.

The Philippine Institute of Volcanology and Seismology (Phivolcs) recorded three rock fall events during the past 24 hours. It also observed moderate emissions of white steam plumes that drifted southeast from Mayon’s crater.

Last Friday, Phivolcs raised Mayon’s alert status from Level 1 to 2 due to episodes of slight inflation, increase of sulfur dioxide emission  beyond baseline levels, and the appearance of a lava dome.

Currently, state volcanologists are closely monitoring the more visible lava dome inside the 200-meter wide crater of Mayon as changes in its size and position to help in the early detection of eruptions.

Ed Laguerta, Phivolcs’ Bicol region chief, said 2014 is an “overdue year” for a very strong eruption. Dating back to a hundred-year span, 1897 and 1814 are the years when Mayon recorded its two deadliest eruptions out of 49 big explosions.

“This 2014 is a hundred years away from the 1897 Vulcanian eruption and 200 years away from Mayon’s 1814 Plenian explosion. By historical accounts, Mayon had been erupting very violently at least at a hundred years interval. It happened twice. It may happen again,” Laguerta warned.

Phivolcs already informed local officials of the possibility of a very strong eruption during their June seminar-workshop, which was also held in commemoration of the bicentennial event of the Feb. 1, 1814 Mayon eruption that buried the Cagsawa Church in Daraga, Albay and claimed at least 1,200 lives.

Mayon’s last eruption was from July 2009 to January 2010, but with no casualty recorded.

Lava dome checks

Laguerta said the agency will capture a series of lava dome images to determine whether the dome is continuously increasing in size and protruding towards the surface.

“Because the moment the dome blocks the crater and the degassing is intense, the possibility of an explosive eruption is very high,” Laguerta told The STAR.

He recounted that the same series of events took place during the eruption in 2000 that was dominated by early episodes of strong, towering and cauliflower-like dark ash columns and debris thrown up to 10 kilometers into the air.

He also clarified that an impending eruption is different from the usual abnormal activities of Mayon when a lava dome is present.

“This is because the lava dome may block the opening of the volcano, like a cork in a bottle full of soda that once shaken by the escaping magma gases would trigger a powerful blast,” the veteran volcanologist warned.

Phivolcs had the first visible view of the lava dome on early morning of Aug. 13. Volcanologists captured the image through a camera installed in a telescope at least 11.5 kilometers away from the institute’s Lignon Hill Observatory in Legazpi City.

“We need to have at least another image of the lava dome at the opposite side of the crater to precisely determine its size and position,” Laguerta said.

Unfortunately, two aerial surveys conducted via helicopter of the Philippine Air Force failed to capture the needed images of the crater due to thick steam emission and clouds covering the summit.