Philippine Standard Time

00 volcano icon for bulletin  In the past 24-hour period, slow effusion of lava from the summit crater of Mayon Volcano continued to feed and bulk up established lava flows on the Mi-isi (south), Basud (eastern), and Bonga (southeastern) gullies. The two former lava flows have maintained distal lengths of approximately 2.8 kilometers and 600 meters from the crater, while the Bonga lava flow advanced to approximately 2.7 kilometers. Rockfall and pyroclastic density currents or PDCs generated by collapses of the lava flow margins as well as of the summit dome deposited debris still within four (4) kilometers of the crater. Short-lived lava ejection that lasted 28 seconds accompanied by seismic and infrasound signals also occurred at 07:56 PM 21 July 2023. In total, twenty-two (22) LFVQs including one (1) short-lived lava ejection with an ashing event, as well as four (4) PDCs and one hundred seventy-five (175) rockfall events, were recorded by the Mayon Volcano Network. Volcanic sulfur dioxide (SO2) emission averaged 1,758 tonnes/day yesterday, 21 July 2023. Short-term observations from electronic tilt and GPS monitoring indicate a deflation of the eastern lower flanks in early July 2023 and inflation of the northwest middle flanks in the third week of July 2023. Longer-term ground deformation parameters from EDM, precise leveling, continuous GPS, and electronic tilt monitoring indicate that Mayon is still generally inflated relative to baseline levels.


Alert Level 3 is maintained over Mayon Volcano, which means that it is currently in a relatively high level of unrest and hazardous eruption within weeks or even days could still be possible. It is therefore recommended that the 6-km radius Permanent Danger Zone (PDZ) remain evacuated due to the danger of PDCs, lava flows, rockfalls, and other volcanic hazards. Increased vigilance against pyroclastic density currents, lahars, and sediment-laden streamflows along channels draining the edifice is also advised. Heavy rainfall could generate channel-confined lahars and sediment-laden streamflows in channels where PDC deposits were emplaced. Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ash from any sudden eruption can be hazardous to aircraft. Based on the current prevailing wind pattern, ash fall events may most likely occur on the south side of the volcano. DOST-PHIVOLCS maintains close monitoring of Mayon Volcano and any new development will be communicated to all concerned stakeholders.