Attachments
I. Situation Overview
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As of 18 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, very slow effusion of lava from the summit crater of Mayon Volcano continued to feed lava flows and collapse debris on the Mi-isi (south) and Bonga (southeastern) gullies as well as rockfall and PDCs on these and the Basud (eastern) gullies. The lava flows from the summit crater have advanced to approximate lengths of two thousand eight hundred (2800) meters along Mi-isi gully, two thousand four hundred (2400) meters along Bonga gully, and six hundred (600) meters along Basud gully. Meanwhile, collapse debris has deposited to four thousand (4000) meters from the crater along the Basud channel. Three (3) pyroclastic density currents (PDC) generated by dome-collapse, one hundred fifty (150) rockfall events, and two hundred sixty-seven (267) volcanic earthquakes were recorded by the Mayon Volcano Network. Repetitive pulse tremor reoccurred at 11:00PM 16 July 2023 with varying interval, and accompanying infrasonic signals detected with reported audible sounds. Sulfur dioxide (SO2) emission averaged 2,212 tonnes/day on 17 July 2023. Short-term observations from EDM and electronic tiltmeter monitoring show the upper slopes to be inflating since February 2023. Longer-term ground deformation parameters based on EDM, precise leveling, continuous GPS, and electronic tilt monitoring indicate that Mayon is still inflated, especially on the northwest and southeast.
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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, rockfalls, 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.
Source: DOST-PHIVOLCS
II. Status of Affected Areas and Population
A total of 9,867 families or 38,375 persons are affected in 26 barangays in Albay (see Table 1).