Metro Manila (CNN Philippines) — Mount Bulusan in Sorsogon erupted Friday, spewing ash about two kilometers into the sky, the Philippine Institute of Volcanology and Seismology (Phivolcs) said.

The eruption started at 11:35 a.m. and lasted approximately five minutes based on seismic record, Phivolcs said.

Bulusan Volcano Eruption Notification Update: 10June2016 #BulusanVolcano pic.twitter.com/t9ZhiobtX3

— PHIVOLCS-DOST (@phivolcs_dost) June 10, 2016

It said the ash plume was more than 6,500 feet high (1.98 kilometers).

The 1,565-meter Mount Bulusan is one of the 23 active volcanoes in the country.

Phivolcs said the eruption was steam-driven or phreatic, the result of ground water coming into contact with magma. Similar eruptions have been recorded since May last year.

Phivolcs Director Renato Solidum tried to calm the public, telling CNN Philippines, Friday’s event was “less energetic than previous eruptions of Mount Bulusan.”

Solidum: Mas mahina ito sa pinakamalakas na eruption ng Mt. Bulusan sometime June. https://t.co/sDo55hOx53 https://t.co/yeonltRRoF

— CNN Philippines (@cnnphilippines) June 10, 2016

 

Mt. Bulusan remains under alert level 1, Phivolcs said.

Solidum reminded the public not to enter a “4-kilometer radius Permanent Danger Zone” due to possible sudden eruptions. He also warned pilots not to fly close to the volcano’s crater because the volcanic ash is hazardous to aircraft.

Philvolcs said residents living in valleys and close to rivers and waterways especially to the southwest and northwest of the volcano are vulnerable to lahar flows during heavy or prolonged rainfall.

Phivolcs director Renato Solidum gives an update on Mt. Bulusan's eruption. https://t.co/sDo55hOx53 https://t.co/tc7zqklwah

— CNN Philippines (@cnnphilippines) June 10, 2016