Attachments
I. Situation Overview
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As of 29 July 2023 at 8AM, 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.
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In the past 24-hour period, there has been a marked weakening of slow lava effusion from the summit crater of Mayon Volcano that fed lava flows on the Mi-isi (south), Bonga (southeastern), and Basud (eastern) 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 3.1 kilometers. No pyroclastic density currents (PDC) and fewer rockfall events were detected. *
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In total, forty volcanic earthquakes including thirty-nine (39) low-frequency volcanic earthquakes or LFVQs, as well as forty-five (45) rockfall events, were recorded by the Mayon Volcano Network. Volcanic sulfur dioxide (SO2) emission averaged 4,113 tonnes/day on 28 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.
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It is therefore recommended that the 6-km radius Permanent Danger Zone (PDZ) remain evacuated due to the danger of PDCs, lava flows, rock falls, and other volcanic hazards.
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Increased vigilance against pyroclastic density currents, lahars, and sedimentladen 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.
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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.
Note: Detection of PDCs and rock fall has been affected by the powering down of the Anoling, Camalig Observation Station (VMAN) after days of no solar recharging. VMAN is inside the 6-km PDZ and the closest station to the Mi-isi and Bonga Gullies.
Source: DOST-PHIVOLCS