It is comforting that the Civil Aviation Authority of the Philippines has notified pilots to avoid the vicinity of Mayon Volcano after volcanologists on Monday raised to Alert Level 2 its unrest.
This means flights are prohibited to operate 10,000 feet from the surface of the country’s most active of 22 volcanoes and to avoid flying close to the volcano’s summit as ash from the sudden phreatic eruption can be hazardous to aircraft.
In an advisory, the Department of Science and Technology-Phivolcs (Philippine Institute of Volcanology and Seismology) announced there has been an increase in rockfall from the 2,462-meter tall Mayon Volcano’s summit lava dome since the last week of April, from an average of five events per day to 49 events per day from 5 am of Sunday to 5 am of Monday.
Phivolcs advised since 10:30 pm of June 3, visible upwelling of volcanic fluids in the Main Crater Lake produced voluminous steam-rich plumes that rose to 3,000 meters above Taal Volcano Island.
The notice should also be heeded by to towns round the volcano and tourists, local and foreign, intending to see Mayon towards the end of summer while the volcano is in that state of “increasing unrest.”
The volcano, often described as a near perfect cone, is geographically shared by eight cities and towns of Legazpi, Daraga, Camalig, Guinobatan, Ligao, Tabaco, Malilipot, and Santo Domingo, which divide the cone like slices of a pie when viewing a map of their political boundaries.
Mayon, whose most destructive eruption was in 1814 when it killed 1,200 people caused by pyroclastic density currents, port eruption lahars, and fires set alight by hot tephra, draws tourists because of its symmetrical cone shape.
Based on ground deformation parameters from electronic distance measurement, precise leveling, electronic tilt, and continuous GPS (Global Positioning System) monitoring, Mayon Volcano has been slightly “inflated” in ground swelling due to the accumulation of magma since 2020.
Under Alert Level 2, the current unrest driven by shallow magmatic processes could lead to phreatic eruptions or precede hazardous magmatic eruption.
The public is advised to be vigilant and refrain from entering the 6-km radius permanent danger zone to minimize risks from sudden explosions, rockfall and landslides.
Phivolcs said the lava dome has increased in volume by approximately 83,000 cubic meters since Feb. 23, and nearly 164,000 cubic meters since Aug. 20, 2022.
Meanwhile, the highest sulfur dioxide emission was 576 metric tons last April 29, and the last measurement averaged 162 tons last May 23.
“These low-level volcanic earthquakes, ground deformation, and volcanic gas parameters are overshadowed by recent steep increases in rockfall events which may possibly lead to further dome activity,” Phivolcs advisory read.