Water in Taal’s crater boiled before and after its eruption, a video posted on the Facebook page of the seismology agency showed.
Magma made contact with the crater’s water, which then turned into gas and vapor, known as a phreatomagmatic eruption.
“Phreatomagmatic is more dangerous because there’s already an interaction with magma,” Maria Antonia Bornas, chief of the agency’s monitoring and eruption prediction division, told a news conference.
The towns of Agoncillo and Laurel, situated on the lake surrounding the Taal volcano, were in danger from eruption and volcanic tsunami, the seismology agency said.
The national disaster bureau warned of eruption-related quakes.
The evacuation of Agoncillo started late afternoon, Batangas provincial governor Hermilando Mandanas said, con più di 3,500 famiglie — quasi 14,500 persone — to be moved to safe areas.
Dump trucks were sent to assist and pay loaders and evacuation centers were being readied, Ha aggiunto.