The Philippine Institute of Volcanology and Seismology (Phivolcs) raised Alert Level 1 (Abnormal) over Taal Volcano, Mayon Volcano, Kanlaon Volcano, and Bulusan Volcano on Tuesday.

This was imposed after the volcanoes showed a period of unrest, with volcanic earthquakes and steam-laden plumes observed from the four active volcanoes  over the past 24 hours.

Phivolcs has recorded five volcanic tremors from the Taal Volcano Network over the period.

Mayon Volcano was reported to have one rockfall event and moderate emission of steam-laden plumes with a recorded height of 750 meters, state volcanologists said. 

Four volcanic earthquakes were observed from Kanlaon Volcano with steam-laden emissions measuring 500 meters in height, the Phivolcs reported. The sulfur dioxide emission was recorded to be at an average of 1012 tonnes per day on August 2.

The state volcano institute also cited weak emissions of white steam-laden plumes from Bulusan’s lower southeast vent.

Phivolcs warned the public that at Alert Level 1 sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall, and lethal accumulations or expulsions of volcanic gas can occur around the volcanoes’ immediate area.

The agency strongly advised that entry into these areas should be blocked off by Local Government Units (LGUs), and that local authorities should monitor the volcanic activity to assess if an evacuation for residents leaving in nearby areas is needed.

Civil aviation authorities must advise pilots to avoid flying close to these areas, Phivolcs added. Carlito P. Topacio