MANILA (UPDATE)—The Philippine Institute of Volcanology and Seismology (Phivolcs) said late Thursday night it detected an increase in seismic activity at the Bulusan volcano in Sorsogon province.
In an advisory released past 11 p.m., the Phivolcs said that since 5 a.m. on Thursday, at least 45 volcanic earthquakes, including two low-frequency volcanic tremors, have been recorded from the volcano by the Bulusan Volcano Network.
"Most of these were weak and shallow events, but may indicate that a phreatic eruption could possibly occur within the next few hours.
The public is reminded that Alert Level 1 status prevails over Bulusan Volcano, which means that it is currently in an abnormal condition," the state agency said.
Mt. Bulusan had a phreatic or steam-driven eruption on June 5, forcing more than a 100 families to evacuate their homes which were nearby the volcano.
Dozens of families have returned to their residences.
Phivolcs reminded the public and local government units that entering the four-kilometer radius within the volcano, deemed as the Permanent Danger Zone, should be still strictly prohibited.
The agency also called for vigilance within the two-kilometer radius, or the Extended Danger Zone, due to the increased possibilities of sudden phreatic eruptions.
"Civil aviation authorities must also advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft," the Phivolcs said.
"Furthermore, people living within valleys and along river/stream channels especially on the southeast, southwest and northwest sector of the edifice should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall should phreatic eruption occur," it added.
The DOH has released some P84.5 million worth of logistical assistance, which included N95 masks, hygiene kits, assorted medicines and jerry cans for water, said its spokesperson Health Undersecretary Maria Rosario Vergeire.
Routine and COVID-19 vaccinations also took place in evacuation centers, Vergeire added.
COVID-19 testing at the barangay level must be conducted after some 3,280 families or 16,4000 evacuees have returned to their homes, according to the spokesperson.