Manila Bulletin
Philippines
National
Mayon's 'increased' eruptive activity shows more pyroclastic density currents, volcanic quakes
Philippines
National
Mayon's 'increased' eruptive activity shows more pyroclastic density currents, volcanic quakes
Mayon's 'increased' eruptive activity shows more pyroclastic density currents, volcanic quakes
Published Jul 1, 2023 03:23 am
The generation of more pyroclastic density currents (PDCs) as a result of the collapse of a lava dome on Mayon Volcano, as well as the occurrence of more frequent volcanic earthquakes, characterized the “increased” eruptive activity at the restive volcano on Friday, June 30, said State volcanologists on Saturday, July 1.
In its 8 a.m. bulletin on Saturday, the Philippine Institute of Volcanology and Seismology (Phivolcs) reported 17 dome collapse-triggered PDCs and 65 weak volcanic earthquakes at Mayon Volcano on Friday, up from seven PDCs and two tremors the previous day.
According to Phivolcs, the largest of the PDCs was detected on Friday at 1:01 p.m. and lasted eight minutes, while four visible three- to four-kilometer long PDCs lasting about four minutes each were observed between 6 p.m. and 8 p.m.
It added that PDCs cascaded down the Basud Gully on the eastern slope of Mayon Volcano on Friday, producing one-kilometer-high ash clouds.
A series of pyroclastic density currents, or PDCs, began cascading down the Basud Gully on the eastern flank of Mayon Volcano at 6:09 p.m. on June 30, 2023. The PDCs lasted approximately four minutes and traveled three to four kilometers downslope. (Screengrab from Phivolcs)
Ashfall was seen in Tabaco City in Albay province because of Mayon’s eruption.
Phivolcs said PDCs are mixtures of fragmented volcanic particles or pyroclastic, hot gases, and ash that travel at a high-speed down the volcanic slopes or outward from a source vent.
A series of pyroclastic density currents, or PDCs, began cascading down the Basud Gully on the eastern flank of Mayon Volcano at 6:09 p.m. on June 30, 2023. The PDCs lasted approximately four minutes and traveled three to four kilometers downslope. (Screengrab from Phivolcs)
Ashfall was seen in Tabaco City in Albay province because of Mayon’s eruption.
Phivolcs said PDCs are mixtures of fragmented volcanic particles or pyroclastic, hot gases, and ash that travel at a high-speed down the volcanic slopes or outward from a source vent.
‘Very slow’ lava flow persists
“For the past 24-hour observation period, very slow effusion of lava from the summit crater of Mayon Volcano continued to feed lava flows on the Mi-isi (south) and Bonga (southeastern) gullies as well as rockfall and PDCs on these and the Basud (eastern) gullies,” Phivolcs said. Lava flows have progressed along the Mi-isi and Bonga gullies from the summit crater to about 2,230 meters and 1,300 meters, respectively, while collapsed debris has reached 3,300 meters from the crater. About 254 rockfall occurrences were observed in the past 24 hours. Mayon also continuously released large amounts of gas, which resulted in steam-laden plumes that rose 2,000 meters before drifting in an east-northeast and general west direction. Phivolcs also noted that the concentrations of sulfur dioxide (SO2) started to increase on June 29 and were averaging 1,002 tons per day when they were last measured on June 30.‘Magmatic unrest’ intensifies
Mayon Volcano is still under Alert Level 3 as it is “currently in a relatively high level of unrest as magma is at the crater and hazardous eruption within weeks or even days is possible.” Phivolcs strongly recommended the evacuation of residents within the six-kilometer permanent danger zone due to the risk of PDCs, lava flows, rockfalls, and other volcanic hazards. In addition, it advised communities to maintain increased vigilance against PDCs, 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. Pilots were also asked to avoid flying close to the volcano because ash from a sudden eruption may pose hazards to aircraft. According to Phivolcs, communities on the southern side of Mayon Volcano may most likely experience ash fall events based on the current wind pattern.