By Catherine J. Teves
Mayon Volcano on September 23, 1984: Pyroclastic flows descend the south-eastern flank of Mayon Volcano, Philippines. Then, the maximum height of the eruption column was 15 km above sea level, and volcanic ash fell within about 50 km toward the west. There were no casualties from the 1984 eruption because more than 73,000 people evacuated the danger zones as recommended by scientists of the Philippine Institute of Volcanology and Seismology. (Mayon VolcanoPublic Domain C.G. Newhall, Wikipedia)
MANILA (PNA) – A major eruption isn’t yet imminent in Mayon Volcano but this mountain still poses danger due to continuing volcanic activities there.
Philippine Institute of Volcanology and Seismology (Phivolcs) science research specialist Ryan Rebadulla cautioned against such danger, noting rockfalls from earthquakes in Mayon and phreatic eruptions from contact of ground water and this mountain’s hot rocks are among life-threatening occurrences possible anytime and almost without warning.
He said landslides and avalanche at the middle to upper slope as well as sudden ash puffs are also possible in Mayon.
“We advise people to avoid entering Mayon’s permanent danger zone (PDZ),” he said.
The PDZ covers an area with a six-kilometer radius measured from Mayon’s summit.
Rising some 2.46 km in Albay province, Mayon Volcano is considered the world’s perfect cone.
Mayon’s beauty and symmetry is world-famous even if Phivolcs said this volcano already registered around 49 historical eruptions.
Among precursors to such eruptions were increased seismicity level and steam emissions, crater glow due to presence of magma at or near the summit, rumbling sounds caused by gas explosions and ground tilt from magma intrusion, Phivolcs said.
Also observed was change in emissions’ color from white to grey due to entrained ash, Phivolcs said.
Phivolcs, in its bulletin issued on Monday, said that alert level 1 remained hoisted over Mayon Volcano due to low-level unrest.
“Conditions there are abnormal,” said Rebadulla.
He noted emission of white steam plumes was one condition Phivolcs monitored in Mayon.
Earlier, Phivolcs also reported monitoring inflation of Mayon’s edifice and emission of sulfur dioxide there.
Rebadulla said a major eruption in Mayon was possible since this volcano was active.
“There’s still no imminent magmatic eruption in Mayon, however,” he clarified, contradicting earlier media reports about this volcano’s alleged looming major blast.
Phivolcs will raise alert level 4 if it already monitors intense unrest in Mayon.
Such unrest is marked by events like persistent tremors, “intense” crater glow, lava flow in the summit area and sustained increase or abrupt decrease of sulfur dioxide emissions, noted Phivolcs.
Alert level 4 means hazardous eruption of Mayon is already possible within days, Phivolcs continued.
Moderate and relatively high unrest in Mayon will draw alert levels 2 and 3, respectively.
“We’ll raise the alert level corresponding to Mayon’s condition,” said Rebadulla.
Mayon Volcano is among the country’s active volcanoes.
Phivolcs considers as “active” volcanoes that erupted either within the last 600 years as documented by man or within the last 10,000 years based on analysis of datable materials.