Mayon Volcano continued to pour lava from its summit on Sunday, July 12, as state volcanologists warned that a sharp spike in sulfur dioxide (SO₂) emissions could be an early sign of a more explosive phase of unrest.
The Philippine Institute of Volcanology and Seismology (Phivolcs) reported in a monitoring bulletin that the volcano remained in an effusive state, recording 125 volcanic earthquakes and 344 rockfall events over the past 24 hours.
The sustained activity came a day after Phivolcs disclosed that Mayon released an average of 13,128 tons of sulfur dioxide on Saturday, July 11—the highest emission rate recorded at the volcano in the last 26 years and only slightly lower than the levels observed during its explosive 2000 eruption.
According to the agency, the abrupt increase in volcanic gas emissions has been accompanied by more low-frequency volcanic earthquakes, which are associated with magma degassing and minor Strombolian activity at the summit crater, as well as more frequent rockfalls caused by the collapse of newly emplaced lava flows.
Strombolian activity is characterized by short-lived explosive bursts that eject incandescent volcanic fragments and produce brief lava fountains.
While Mayon’s overall behavior remains consistent with ongoing lava effusion, Phivolcs said the unusually high sulfur dioxide emissions could indicate that the volcano is transitioning toward more explosive eruptive activity.
“Elevated volcanic SO₂ emissions could forewarn of further or even a potential shift to explosive eruptive activity at the summit crater that could generate volcanic hazards all around the volcano, the impacts of which can be worsened by the prevailing poor weather conditions,” the agency said.
Mayon remains under Alert Level 3, signifying intensified or magmatic unrest.
PHIVOLCS reminded the public that entry into the six-kilometer Permanent Danger Zone (PDZ) remains prohibited and urged residents in areas vulnerable to pyroclastic density currents to stay prepared should volcanic activity escalate. It also advised communities along river channels to remain alert for lahars and sediment-laden streamflows during prolonged heavy rainfall.
The agency likewise warned pilots to avoid flying near the volcano’s summit due to the risk of sudden ash eruptions and ballistic fragments.*
Reymund Titong is a Filipino journalist steadily building his voice in the field of news reporting, driven by a commitment to tell meaningful and relevant stories.
He serves as a correspondent for Rappler, contributes to Negros Daily Bulletin, and maintains a blog on Medium.