Daily visual and webcam observations of Mayon’s summit crater revealed more frequent rockfalls at the summit lava dome starting in the last week of April, indicating aseismic dome growth. The lava dome increased in volume by about 83,000 cubic meters during 3 February-9 May, with a total addition of nearly 164,000 cubic meters since 20 August 2022. Sulfur dioxide emission averages were as high as 576 tons per day on 29 April and 162 tons per day on 23 May. A total of 26 volcanic earthquakes had been recorded since 1 April. Electronic Distance Measuring (EDM), precise leveling, continuous GPS, and electronic tilt monitoring data showed that the volcano had been slightly inflated, especially on the NW and SE flanks, since 2020. Short-term inflation on the upper flanks had been detected since February.

From 0500 on 4 June to 0500 on 5 June the number of rockfalls increased from an average of 5 events per day to 49 events per day. At 1000 on 5 June the Alert Level was raised to 2 (on a 0-5 scale). PHIVOLCS noted that although low-level volcanic earthquakes, ground deformation, and volcanic gas emissions indicated unrest, the steep increase in rockfall frequency may indicate increased dome activity. Residents were reminded to stay away from the 6-km-radius Permanent Danger Zone (PDZ).

Geological Summary. Symmetrical Mayon, which rises above the Albay Gulf NW of Legazpi City, is the most active volcano of the Philippines. The steep upper slopes are capped by a small summit crater. Recorded eruptions since 1616 CE 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 damaged populated lowland areas. A violent eruption in 1814 killed more than 1,200 people and devastated several towns.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)