Mayon Volcano's Muddy Flow Triggers Lahar Threat in Albay

LEGAZPI CITY — The Philippine Institute of Volcanology and Seismology (Phivolcs) has warned the public to stay away from river channels around Mayon Volcano after a muddy stream flow, believed to be lahar, was recorded along the Mi-isi Channel in Daraga, Albay. A resident of Barangay Salvacion, near the Mi-isi Gully in Barangay Mi-isi, captured on video on Thursday, July 16, a muddy flow rushing down the volcano’s slopes. Ma. Antonia Bornas, chief of Phivolcs’ Volcano Monitoring and Eruption Prediction Division, said the flow was likely caused by accumulated volcanic deposits being washed downstream. “These were likely lahars in the upper slopes that became diluted into muddy stream flows by the time they reached the lower areas,” Bornas said during a briefing with Albay officials on Friday. She explained that low-level, channel-confined lahars have been gradually clearing loose volcanic deposits from the upper slopes but warned that prolonged or heavy rainfall could mobilize the remaining materials and trigger more destructive lahars. READ: Mayon’s rumbling stirs fear among Albay folk Bornas said volcanic ash and other deposits have accumulated as far as 5.4 kilometers along the Binaan Channel following the massive lava collapse at the Mi-isi Gully on May 2. The collapse generated pyroclastic density currents that blanketed the towns of Camalig and Guinobatan, and Ligao City with heavy ashfall. READ: Phivolcs warns of ashfall amid lava collapse in Mayon Daraga Mayor Victor Perete said volcanic debris, in some areas more than 50 meters deep, has accumulated near the Green Lava all-terrain vehicle site in Barangay Mi-isi. He said village officials requested the desilting of the lahar channel, which has become shallow due to the continuous buildup of volcanic materials. “Quarry operators may be tapped to clear and desilt the channel because it has already become shallow. This will help keep lahar flows confined to the existing channel and prevent them from spilling into other areas,” Perete told the Inquirer in a phone interview on Saturday. Although the recent muddy flow in Barangay Salvacion remained within the existing channel, Perete warned that the huge volume of volcanic deposits on Mayon’s upper slopes could alter the lahar’s path if the channels are not cleared. Nonito Alemania, village chief of Barangay Mi-isi, said residents have been advised to avoid the Binaan River and stay away from the six-kilometer Permanent Danger Zone (PDZ). “There are no residents in the area, but if the lahar changes course, communities in the lower grounds could be at risk,” Alemania said in a separate phone interview. He added that village watchmen have been deployed to secure the PDZ and monitor the river channels. Mayon’s eruptive activity intensified on July 13 with a series of more energetic Strombolian eruptions, accompanied by fresh lava flows, increased rockfall activity, and pyroclastic density currents, according to Phivolcs. /mcm