State volcanologists warned the public that they have monitored more earthquakes at Taal Volcano in the province of Batangas, an indicator "increasing the possibilities of [a] magmatic eruption."
The Philippine Institute of Volcanology and Seismology (Phivolcs) said in an advisory on Wednesday, March 24, that the Taal Volcano Network has recorded 2,015 volcanic tremors, 734 low-frequency volcanic earthquakes, and 18 hybrid earthquakes since February 13.
Phivolcs added that harmonic tremors "associated with magma migration" or the movement of magma "has become the dominant type of earthquake" since Friday, March 19.
Most earthquakes were shallow, at less than 2 kilometers deep, but "some large earthquakes were generated in the deeper 2- to 6-kilometer region beneath the Taal Volcano Island edifice," said Phivolcs.
The agency added that "overall seismic energy release has markedly increased" since Tuesday afternoon, March 23, "compared to previous seismic swarms" or clusters of earthquakes.
The emission of sulfur dioxide, a major gas component of magma, has also been "generally high" in the past week. It peaked at 1,184 tons per day on Sunday, March 21.
Under Alert Level 2, Phivolcs warned that the following could occur:
The agency said entry into Taal Volcano Island, and "occupancy and boating on Taal Lake," should remain strictly prohibited.
"Local government units are advised to continuously assess and strengthen the preparedness of previously evacuated barangays around Taal Lake in case of renewed unrest," added Phivolcs.