MANILA – The Philippine Institute of Volcanology and Seismology (Phivolcs) on Tuesday said the likelihood of raising Taal Volcano's alert status to level 4 is "not too high".

Phivolcs chief science research specialist Ma. Antonia Bornas said activity at the main crater of Taal was dominated by an upwelling of hot volcanic fluids in its lake which generated plumes 2,400 meters tall. Sulfur dioxide (SO2) emission averaged 4,273 tonnes on Monday.

Taal Volcano has been under alert level 3 (magmatic unrest) since Saturday, indicating there is magmatic intrusion at the main crater that may further drive succeeding eruptions, she noted.

Three phreatomagmatic bursts were also detected in the Taal Volcano during the 24-hour observation period.

These eruptions occurred at 9:30 a.m., 9:33 a.m. and 9:36 a.m. on Monday, and produced plumes 400 meters to 800 meters high.

Phreatomagmatic eruptions are caused by the interaction of magma and water. Eruptions normally consist of multiple explosive events, the interval of which may vary.

Eight volcanic earthquakes caused by movements or eruptions of magma from the volcano were also detected in the past 24 hours. The figure includes one volcanic tremor that lasted for five minutes, and seven low-frequency volcanic earthquakes.

Bornas said Taal Volcano being under alert level 3 may be sustained if similar phreatomagmatic activity recurs, or may be put under alert level 2 (increasing unrest) if no phreatomagmatic activity occurs in the next two weeks,

Meanwhile, Phivolcs has recommended that those in Taal Volcano Island (TVI) and high risk barangays of Bilibinwang and Banyaga, Agoncillo and Boso-Boso, Gulod and eastern Bugaan East, Laurel, Batangas be evacuated due to the possible hazards of pyroclastic density currents and volcanic tsunami should stronger eruptions subsequently occur.

Entry into TVI and high risk barangays Agoncillo and Laurel must be prohibited. Further, all activities on the Taal Lake should be barred, Phivolcs added.

Communities around the Taal Lake shores are likewise advised to remain vigilant, take precautionary measures against possible airborne ash and vog, and calmly prepare for possible evacuation should unrest intensify.

Vog or volcanic smog is a type of air pollution caused by volcanoes. It consists of fine droplets containing volcanic gas such as sulfur dioxide which is acidic and can cause irritation of the eyes, throat, and respiratory tract in severities depending on the gas concentrations and durations of exposure. (PNA)