SORSOGON, Philippines — The Philippine Institute of Volcanology and Seismology (PHIVOLCS) raised the status of Bulusan Volcano to Alert Level 1 on Sunday, March 22, 2026. The move comes after a significant increase in volcanic earthquakes and visible swelling of the volcano’s structure, indicating low-level unrest.
- Seismic Activity: PHIVOLCS recorded 475 volcanic earthquakes since March 15. These are classified as weak volcano-tectonic tremors caused by rocks breaking at shallow depths—a pattern similar to the seismicity observed before the June 2022 and April 2025 eruptions.
- Ground Deformation: Data shows inflation (swelling) on the western and southeastern flanks of the volcano, starting as early as late January 2026.
- Gas Emissions: Sulfur dioxide (SO2) emissions averaged 91 tons per day as of mid-March, accompanied by weak to moderate degassing from active vents.
The volcano is currently experiencing “hydrothermal processes” where underground water is being heated by volcanic gases or rocks. This increases the likelihood of phreatic eruptions—sudden, steam-driven explosions that can occur without warning from any of the summit vents.
- Permanent Danger Zone (PDZ): Entry into the 4-kilometer radius is strictly prohibited due to the risk of sudden explosions, rockfalls, and landslides.
- Extended Danger Zone (EDZ): Increased vigilance is required within the 2-kilometer zone on the southeast sector.
- Aviation Warning: Civil aviation authorities have been advised to instruct pilots to avoid flying near the summit, as ash from sudden eruptions can severely damage aircraft engines.
- Lahar Awareness: Residents in valleys and along river channels (southeast, southwest, and northwest) should watch for lahars or sediment-laden stream flows, especially during heavy rainfall.
Communities to the west of the volcano are also advised to prepare for potential ashfall should a minor eruption occur. Local government units are currently on standby to implement contingency plans if volcanic activity escalates further.