Mount Bulusan: active stratovolcano in Sorsogon, Philippines

Physical characteristics

Bulusan has the steep conical profile of a stratovolcano with a distinct summit crater and areas of fumarolic and hydrothermal activity on its flanks. The lower slopes are covered with tropical and montane forest that give way to altered and less vegetated ground nearer the summit where hot gases and acid alter soil and plants. The mountain’s watershed supports rivers and springs important to nearby communities.

Geology and activity

The volcano formed in a subduction zone setting where oceanic crust descends beneath the Philippine archipelago, producing magmas that feed both magmatic and steam-driven eruptions. Historical activity at Bulusan has been characterized largely by short-lived phreatic events and minor ash-bearing explosions; larger magmatic eruptions are less common but remain a possibility in volcanic systems such as this.

Hazards and monitoring

Hazards associated with Bulusan include ashfall, ballistic fragments near vents, volcanic gases and secondary threats such as lahars during heavy rain. The Philippine volcanological agency conducts continuous surveillance, issues alert levels, and coordinates with local authorities on public warnings and evacuation plans. Residents and visitors are advised to follow official guidance when activity increases.

Conservation and human use

Mount Bulusan lies within a designated protected area that conserves native flora and fauna and functions as an important watershed. The park attracts hikers and nature visitors when the volcanic alert level permits access; access is restricted during heightened activity. Conservation and community preparedness are central to balancing ecological protection, recreation and public safety.

Research and education

Scientists monitor Bulusan using seismic, gas and ground-deformation measurements to better understand its behavior and to provide early warning. Educational outreach emphasizes volcano hazards, emergency planning and the ecological value of the surrounding natural park.

• Type: active stratovolcano in the Bicol Volcanic Arc.
• Common activity: phreatic explosions and small ash emissions.
• Importance: watershed protection, biodiversity, and local livelihoods.