Mayon gas levels peak explosion risk rises

By Michael B. Jaucian

LIGAO CITY --- A record surge in sulfur dioxide (SO₂) emissions from Mayon Volcano has heightened the possibility of a more explosive eruption, the Philippine Institute of Volcanology and Seismology (Phivolcs) warned on Saturday.

Mayon emitted an average of 13,128 metric tons of volcanic SO₂ per day on July 11, based on campaign ultraviolet spectrometry measurements conducted by Phivolcs.

The agency said the emission rate was the highest recorded from the volcano in the past 26 years and was only slightly below the levels observed during Mayon's explosive eruption in 2000.

Mayon remains under Alert Level 3 and has been in a state of continuous eruption for 187 days.

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LATE BREAKER

A short-lived lava fountaining was observed at the summit crater of Mayon Volcano on Monday afternoon, July 13. The lava fountaining, recorded from 3:25 p.m. to 3:27 p.m., was captured on video by the Quick Response Team of the Philippine Institute of Volcanology and Seismology (Phivolcs) and the Mayon Volcano Observatory.

Phivolcs said Mayon has now been exhibiting effusive eruptive activity for the 189th consecutive day, producing incandescent lava flows, pyroclastic density currents (PDCs), locally known as uson, and rockfalls.

Earlier in the day, between 6:31 a.m. and 6:46 a.m., the volcano generated another pyroclastic density current.

Alert Level 3 remains in effect over Mayon Volcano, and entry into the six-kilometer Permanent Danger Zone (PDZ) is still prohibited.

Mayon continues to emit pyroclastic density current.

Mayon, one of the country’s most active volcanoes, has been in sustained eruptive activity for months already, with monitoring continuing around the clock for any signs of changes in its behavior.

Over the weekend, Phivolcs warned that the record surge in sulfur dioxide (SO2) emissions from Mayon Volcano has raised the possibility of a more explosive eruption. Kurt Dela Peña/Inquirer

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Mayor Daniel Jose “Nookie” Bombales said residents experienced thin ashfall Saturday afternoon as strong winds and rains associated with the enhanced southwest monsoon and Typhoon Inday affected the area.

The local government and police distributed face masks to residents in affected communities on Friday night.

Bombales urged residents to wear face masks when going outdoors and to keep windows and doors closed whenever possible.

In its Saturday bulletin, Phivolcs reported 10 volcanic earthquakes, 241 rockfall events, and six pyroclastic density current signals.

The agency also observed continuing lava flows that extended about 3.8 kilometers along the Basud Gully, 3.2 kilometers along the Bonga Gully, and 2.1 kilometers along the Mi-isi Gully.

Phivolcs said the spike in SO₂ emissions coincided with intensified volcanic activity, including 97 low-frequency volcanic earthquakes associated with volcanic degassing, minor Strombolian activity at the summit crater, and 304 rockfall events caused by the collapse of newly emplaced lava flows as of 8 p.m. Saturday.

Despite the increased activity, the agency said monitoring data showed only slight inflation of the volcanic edifice and a modest increase in overall seismic energy, conditions still consistent with the effusive eruption that has characterized Mayon since the onset of its 2026 unrest.

However, Phivolcs warned that the exceptionally high SO₂ emissions could indicate a shift in eruptive behavior and may “even lead to an explosive eruption.”

Such an event, the agency said, could generate larger and farther-reaching pyroclastic density currents on all sectors of the volcano, hurl ballistic rock fragments from the summit crater, and produce more widespread ashfall. The impacts, it added, could be worsened by prevailing adverse weather conditions. (With reports from Ma. April Mier-Manjares - @inquirerdotnet)

MAYON VOLCANO