Mt. Bulusan in Sorsogon continues to show increasing signs of unrest that might lead to an eruption as its emissions of noxious gases are close to breaching critical levels, government volcanologists said yesterday.
Bulusan’s sulfur dioxide emission in the past 24 hours nearly reached the 500 tons per day baseline, indicating the volcano’s “increasing unrest,” the Philippine Institute of Volcanology and Seismology (Phivolcs) said.
Phivolcs also recorded 62 high frequency volcanic earthquakes, compared to only 27 the previous day.
It added that the volcano inflated by about three millimeters at its southern flank.
Phivolcs said Bulusan emitted white steam clouds rising to a height of 50 to 150 meters above the active craters and fissures and drifting to the northwest and northeast.
“The high level of seismic activity and the observed inflation indicate increasing volcanic unrest,” Phivolcs said.
Alert Level 2 remains hoisted around Bulusan, which means the public should not enter the four-kilometer radius permanent danger zone (PDZ) due to sudden steam or ash explosions.
Phivolcs also warned that communities beyond the PDZ will likely be affected by ashfalls during explosions.
Residents near rivers or streams around the volcano should be on alert against life-threatening lahar and flash floods during heavy rains, which may sweep down ash deposits from the volcano’s upper slopes, Phivolcs said.
Last Tuesday afternoon, heavy rains triggered lahar flows into the Rangas-Añog channel in Juban towns and the Cogon-Mapaso and Gulang-Gulang channels in Irosin town.
But resident volcanologist Delia Tubianosa said the lahar flows were confined and did not affect populated areas.
Phivolcs raised Bulusan’s alert level from 1 to 2 last Sunday after it recorded over 200 volcanic quakes and ground deformation the previous day.
Phivolcs director Renato Solidum earlier said they would install two additional seismic stations on Bulusan’s south-southwest and western slopes. The institute has three existing stations.
Bulusan has had 19 eruptions since 1852. – With Cet Dematera