Weak, shallow volcanic quakes persist in Mayon — Phivolcs
Published Jul 20, 2023 05:04 am
The Philippine Institute of Volcanology and Seismology (Phivolcs) said on Thursday, July 20 that low-frequency volcanic earthquakes (LFVQs) associated with the discrete and rapid releases of volcanic gas dominated Mayon Volcano’s eruptive activity in the past 24 hours.
A total of 90 LFVQs were recorded by the Mayon Volcano Network between 5 a.m., Wednesday, July 19 and 5 a.m., Thursday, July 20.
“Some of these degassing events were accompanied by entrained ash at the crater to produce ‘ashing’ that drifted southwest,” Phivolcs said.
Three ashing events were recorded between 10:52 p.m. on July 19 and 12:33 a.m. on July 20, where each event lasted 10 to 25 seconds and ejected a plume that reached a height of 100 meters.
Mayon Volcano ejects massive pyroclastic density currents (PDC) toward the Basud Gully in Sto. Domingo town in Albay province around 5:30 p.m. on July 10, 2023. (Niño Luces/Manila Bulletin)
Mayon Volcano ejects massive pyroclastic density currents (PDC) toward the Basud Gully in Sto. Domingo town in Albay province around 5:30 p.m. on July 10, 2023. (Niño Luces/Manila Bulletin)
Sustained lava flows, rockfalls, PDCs
Phivolcs noted that the slow lava effusion continued to feed and bulk up lava flows on Mi-isi, Bonga, and Basud gullies on Mayon Volcano’s southern, southeastern, and eastern flanks. “These lava flows have maintained distal lengths of approximately 2.8 kilometers, 2.4 kilometers, and 600 meters from the crater, respectively,” it said. Phivolcs said rockfall and pyroclastic density currents (PDCs) caused by the collapse of the summit dome and the lava flow margins left debris four kilometers from the crater. In the past 24 hours, three PDCs and 169 rockfall occurrences were recorded by the Mayon Volcano Network. However, Phivolcs pointed out that the combined seismic energy release from volcanic earthquakes, rockfalls, and PDCs has not gone above the trend of effusive activity.Heightened magmatic unrest persists
According to Phivolcs, Mayon Volcano is still at alert level 3, indicating that it is still in a relatively high level of unrest and that a potentially hazardous eruption may occur within weeks or even days. Communities near the restive volcano are recommended to maintain increased vigilance against lahars and sediment-laden stream flows along channels draining the volcano edifice, as heavy rainfall could cause channel-confined lahars and sediment-laden stream flows. Since Mayon Volcano’s status was upgraded twice in the past month, first to level 2 on June 5 and then to level 3 on June 8, Phivolcs strongly advised that entry into the six-kilometer permanent danger zone be strictly prohibited. Furthermore, it warned that ash fall may occur in areas south of Mayon Volcano due to current wind patterns. Phivolcs advised pilots to avoid flying near the volcano’s summit because ash from a sudden eruption can be dangerous to aircraft.