Mayon Volcano logs 372 rockfall events in past 24 hours
Published Jun 28, 2023 02:32 am
The Philippine Institute of Volcanology and Seismology (Phivolcs) recorded 372 rockfall occurrences in Mayon Volcano between 5 a.m., Tuesday, June 27, and 5 a.m. Wednesday, June 28.
The “very slow” effusion of lava from Mayon Volcano occasionally causes the lava front to collapse, resulting in rockfall events.
“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. The lava flows have advanced to approximate lengths of 1,600 meters and 1,200 meters along Mi-isi and Bonga gullies, respectively, from the summit crater while collapse debris has deposited to 3,300 meters from the crater,” Phivolcs said in its 8 a.m. bulletin on Wednesday.
In addition to rockfalls, seven dome-collapse pyroclastic density currents (PDCs) lasting three minutes were observed.
According to Phivolcs, PDCs are mixtures of fragmented volcanic particles or pyroclastics, hot gases, and ash that rush down the volcanic slopes or rapidly outward from a source vent at high speeds.
Meanwhile, only one volcanic earthquake was recorded in Mayon Volcano in the last 24 hours.
Over the weekend, Phivolcs had noticed an increase in the frequency of shallow and weak volcanic earthquakes in Mayon Volcano, which began on June 24 and continued until around 5 p.m. on June 26.
The restive Mayon Volcano spews steam-laden plumes visible from Sumlang Lake in Camalig and Legazpi City Albay on June 16, 2023. (ALI VICOY/MANILA BULLETIN)
Alert level 3 still in effect
Phivolcs noted that Mayon Volcano’s current condition might last for a few months, therefore Alert Level 3 will remain in effect. This means that Mayon 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 (PDZ) due to the risk of PDCs, lava flows, rockfalls, and other volcanic hazards. “Local government units, disaster officials, and the general public are urged to heed avoidance of the PDZ, as the summit lava dome has grown above and filled up the summit crater, increasing the chances of lava collapse or potential volcanic flows onto other sectors of the volcano,” Phivolcs warned. It pointed out that heavy rainfall could cause channel-confined lahars and sediment-laden stream flows on channels where PDC deposits were emplaced. Likewise, it said that ash fall events may “most likely” occur on the south side of the volcano, based on the current wind pattern. Phivolcs advised civil aviation authorities to ask pilots to avoid flying close to the volcano because ash from sudden eruption may pose hazards to aircraft.