Phivolcs detects increase in seismic activity in Mayon Volcano
Published Jun 26, 2023 09:09 am
The Philippine Institute of Volcanology and Seismology (Phivolcs) began to notice an increase in the frequency of weak and shallow volcanic earthquakes in Mayon Volcano.
“An increasing number of weak and shallow volcanic earthquakes began on June 24, 2023 and steadily increased to 102 volcanic earthquakes during a 24-hour [monitoring] between June 25 and 26, 2023,” Phivolcs said in an advisory that was released at 4 p.m. on Monday, June 26.
An additional 100 volcanic earthquakes have been recorded between 5 a.m. and 3 p.m. on Monday.
“Some of the analyzed earthquakes that could be located emanated from the summit lava dome, indicating origins from lava extrusion processes at the crater,” Phivolcs said.
A very slow effusion of lava from the summit crater of Mayon Volcano continued to feed lava flows and cause debris to collapse on the Mi-isi and Bonga gullies on the south and southeastern sides of the crater, respectively, as shown in this image taken on Saturday evening, June 24, 2023. (Phivolcs)
A very slow effusion of lava from the summit crater of Mayon Volcano continued to feed lava flows and cause debris to collapse on the Mi-isi and Bonga gullies on the south and southeastern sides of the crater, respectively, as shown in this image taken on Saturday evening, June 24, 2023. (Phivolcs)
Quakes causing ground deformation
Phivolcs said that ground deformation in Mayon Volcano also increased significantly over the weekend. Ground deformation refers to the changes on the surface of a volcano due to magma movement, pressurization and depressurization in the hydrothermal system, movement of local faults and other factors, Phivolcs said. “The increased seismicity was accompanied by a noticeable sharp jump in ground tilt on the southwest sector of the edifice that began on June 25, 2023,” it pointed out. According to Phivolcs, Mayon Volcano continues to show “steady-rate lava effusion from the summit crater and sporadic generation of rockfall and pyroclastic density currents (PDCs).” Since Mayon Volcano’s alert status was raised to level 3 on June 8, Phivolcs has observed that eruptive activity has been dominated by “weak aseismic effusion of degassed lava” from the crater. It reiterated that Mayon Volcano still has an “increased tendency toward a hazardous eruption,” but that “sudden change in monitoring parameters has been detected and is being closely monitored.”6-km permanent danger zone remains off-limits
Phivolcs strongly advised that the six-kilometer permanent danger zone must remain off-limits 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. Meanwhile, it recommended that communities within the seven- and eight-kilometer radius to be prepared at all times. 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.