THE Bulusan volcano in Sorsogon province in Luzon erupted Friday, June 10, and several areas nearby, particularly Casiguran, are expected to be hit by ash fall.

Renato Solidum, director of the Philippine Institute of Volcanology and Seismology (Phivolcs), said in a television interview that the phreatic eruption happened around 11:35 a.m. Friday and lasted for five minutes.

Phreatic eruptions are "steam-driven explosions that occur when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or new volcanic deposits," according to the US Geological Survey.

Solidum said the eruption is normal for an active volcano like Bulusan, but it could be dangerous if there are people living inside the four-kilometer permanent danger zone.

"The volcano is still undergoing some processes... The water inside is being boiled," he said.

He said the eruption Friday produced a two-kilometer ash column, adding that Phivolcs is monitoring possible ash fall in Casiguran and villages toward the northwest.

The Phivolcs, in an advisory Friday, reminded the public against entry into the four-kilometer radius permanent danger zone "due to the possibility of sudden and hazardous steam-driven or phreatic eruptions."

The Bulusan volcano also erupted in May last year. (LMY/Sunnex)