The Philippine Institute of Volcanology and Seismology (PHIVOLCS) on Sunday announced an "ongoing phreatic eruption" at Bulusan Volcano in Sorsogon.

"This is to notify the public and concerned authorities of an ongoing phreatic eruption at Bulusan Volcano. Details to follow," said PHIVOLCS in a tweet.

In a separate volcano advisory from the National Disaster Risk Reduction and Management Council, the eruption took place starting at 10:30 a.m. on Sunday.

Phreatic eruptions are "steam-driven explosions that occur when water beneath the ground or on the surface is directly heated by hot rocks or new volcanic deposits or indirectly by magma or magmatic gas," according to PHIVOLCS.