MANILA, Philippines – Just five days after warning of increased activity at Bulusan Volcano, the Philippine Institute of Volcanology and Seismology (Phivolcs) raised the volcano’s status to Alert Level 1 on Wednesday afternoon, October 12.

Prior to Wednesday’s move, Bulusan had been under Alert Level 0, the lowest level, since August 21.

Phivolcs said Alert Level 1 means the volcano in Sorsogon “is currently in a state of low-level unrest.”

The agency observed the following:

• Volcanic earthquakes – 126 weak and shallow (up to 5 kilometers deep) volcanic earthquakes since 5 am, Tuesday, October 11, mostly “attributed to rock-fracturing processes within the edifice”
  
• Ground deformation – “short-term inflation” or swelling of Bulusan’s southern flanks since April as well as a “pronounced and ongoing inflationary trend” that began late September on the volcano’s southwestern and southern slopes
  
• Volcanic carbon dioxide – increasing since July
  
• Sulfurous odor – reported by residents of Sitio Talistison, Barangay Mapaso, Irosin, and Barangay San Roque, Bulusan, on Monday, October 10, and Tuesday, October 11

Phivolcs reminded the public not to enter the 4-kilometer-radius permanent danger zone surrounding the volcano.

The agency also called for vigilance in the 2-kilometer extended danger zone, citing “the increased possibilities of sudden and hazardous phreatic eruptions.”

In addition, Phivolcs warned “people living within valleys and along river or stream channels” that ash from possible phreatic eruptions may mix with rain, which could trigger lahar.

Previous phreatic or steam-driven eruptions in June had caused ashfall in parts of Sorsogon. Lahar also formed along a creek back then.

Ash can be hazardous to aircraft as well. – Rappler.com