Hazardous magmatic eruption possible at Mayon volcano, Alert Level raised to 2, Philippines

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) raised the Alert Level for the Mayon volcano from Level 1 to Level 2 on June 5, 2023, indicating increased volcanic unrest that may potentially precede hazardous eruptions.

PHIVOLCS has reported an increase in the frequency of rockfall events from the Mayon volcano’s summit lava dome, prompting the institute to raise the volcano’s Alert Level from 1 to 2. This increase in activity suggests that there is ongoing unrest driven by shallow magmatic processes that could lead to phreatic eruptions or even precede a hazardous magmatic eruption​.

Over the past month, monitoring of the volcano has shown an increase in rockfall events, rising from an average of 5 per day to 49 per day between June 4 and 5. This rise in rockfall frequency indicates the growth of the summit lava dome.

As of May 9, the lava dome had increased in volume by approximately 83 000 m³ (2.9 million ft³) since February 3 and a total of nearly 164 000 m³ (5.8 million ft³) since August 20, 2022.

PHIVOLCS has recorded a total of 318 rockfall events since April 1, and 26 volcanic earthquakes for the same period. Ground deformation parameters based on electronic distance measurement (EDM), precise leveling, continuous GPS, and electronic tilt monitoring show that the volcano has been inflating, particularly on the northwest and southeast, since 2020.

The public is urged to remain vigilant and avoid the 6 km (3.7 miles) radius Permanent Danger Zone (PDZ) around the volcano to minimize risks from sudden explosions, rockfall, and landslides. Should ash fall events occur, residents are advised to cover their nose and mouth with a damp, clean cloth or dust mask. Civil aviation authorities are also advised to instruct pilots to avoid flying close to the volcano’s summit, as ash from any sudden eruption could be hazardous to aircraft​¹​.

In response to the escalating situation, the Department of Social Welfare and Development (DSWD) has directed its regional offices in Bicol to prepare family food packs as part of emergency measures. DSWD Secretary Rex Gatchalian stated that the offices have been directed to stockpile Family Food Packs and ensure that they have sufficient standby funds. The regional offices have also been tasked with tracking the number of affected families and municipalities, and the duration of the volcanic unrest​.

Geological summary

Beautifully symmetrical Mayon volcano, which rises to 2 462 m (8 077 feet) above the Albay Gulf, is the Philippines’ most active volcano.

The structurally simple volcano has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. Historical eruptions at this basaltic-andesitic volcano date back to 1616 and range from strombolian to basaltic plinian, with cyclical activity beginning with basaltic eruptions, followed by longer-term andesitic lava flows.

Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks.

Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas.

Mayon’s most violent eruption, in 1814, killed more than 1 200 people and devastated several towns.²

References:

¹ MAYON VOLCANO BULLETIN – PHIVOLCS – June 5, 2023

² Mayon – Geological summary – GVP

Featured image credit: PHIVOLCS

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