LEGAZPI CITY, June 23 (PNA) -- Mount Bulusan in Sorsogon on Thursday spewed a dirty white ash plume that drifted towards the town of Juban, the Philippine Institute of Volcanolgy and Seismology (Phivolcs) said.
Ed Laguerta, Phivolcs resident volcanologist, said the volcanic event was phreatic or steam-driven, exhibiting a vigorous steaming activity due to hydrothermal pressure building at the volcano’s vent.
“The dirty white plume suggests a low-energy ash emission,” Laguerta said.
In a text message, he said the ash ejection was observed visually at around 9 a.m. Thursday and lasted for about 18 minutes.
Before and during the ash emission, Phivolcs' instruments indicated that the event was a shallow volcanic episode as no seismic signal was detected.
"The instruments did not detect any seismic activity underneath the volcano, indicating a shallow volcanic source," Laguerta said.
Raden Dimaano, Sorsogon PDRRMC chief, said in a phone interview that only a minimal volume of ash drifted towards Juban town.
He said there is no need yet to call for an evacuation of residents. However, he said precautionary measures have been put in place should the condition worsen.
Alert level 1 (abnormal) remains in effect and the Phivolcs warned villagers not to enter the 4-km Permanent Danger Zone (PDZ) as sudden steam-driven explosion may occur.
It also advised residents living near river channels to be on alert for lahar flows in case of heavy rains.
It further advised pilots not to fly their aircraft near the volcano summit. (PNA) LAP/FGS/MSA/CBD/RSM