Mayon volcano. Photo courtesy of Camalig Information Office.
Mayon Volcano registered a sharp rise in sulfur dioxide emissions alongside changes in earthquake and ground deformation readings, signaling the possibility of another period of eruptive unrest, state volcanologists said Friday.
Sulfur dioxide released by the volcano reached 8,165 tonnes per day on Thursday, nearly twice the 4,196-tonne daily average observed since Mayon was placed under Alert Level 2 on Aug. 5, according to the Philippine Institute of Volcanology and Seismology.
The latest measurement was also the second-highest since gas emissions began trending downward on July 16. Mayon remained at Alert Level 2, which signifies moderate volcanic unrest.
Monitoring instruments separately detected four low-frequency volcanic earthquakes associated with the movement or release of volcanic gases. Despite the increase, overall seismic energy remained within background levels.
Phivolcs also observed short-term inflation or pressurization on the northern and eastern portions of the volcano, another development being monitored for indications of changing activity beneath Mayon.
Taken together, the latest observations suggested that eruptive activity at the summit could recur. Phivolcs warned that an escalation could expose surrounding areas to pyroclastic density currents, falling rocks, ballistic fragments and substantial ashfall.
With adverse weather affecting the area, authorities were also advised to prepare for lahars and sediment-heavy flows along channels around Mayon during prolonged or intense rainfall. Such hazards could become more serious if heavy rain coincided with explosive volcanic activity.
Phivolcs maintained the six-kilometer Permanent Danger Zone around Mayon and urged communities in identified hazard areas to remain prepared should conditions warrant an increase to Alert Level 3. The agency said it would continue monitoring the volcano for further changes.