Bulusan Volcano in Sorsogon continued to show signs of “increased seismicity” in the past 24 hours, with state volcanologists warning people of another possible phreatic or steam-driven eruption.

In its 8 a.m. bulletin issued on Friday, June 10, the Philippine Institute of Volcanology and Seismology (Phivolcs) said 149 volcanic earthquakes were recorded at Bulusan Volcano in the past 24 hours.

It has also detected a 100-meter-high “moderate” emission from the volcano.

Moreover, Bulusan Volcano’s sulfur dioxide or SO2 emission averaged 824 tons per day on June 9.

Phivolcs said the active volcano remains under Alert Level 1, which means there is a “slight increase” in volcanic earthquake and steam or gas activity.

Bulusan Volcano’s status has been raised from Level 0 to Level 1, following a phreatic eruption on June 5, which produced an ash plume more than a kilometer-high and left parts of Sorsogon blanketed in ash.

“Local government units and the public are reminded that entry into the four-kilometer radius permanent danger zone must be strictly prohibited and that vigilance in the two-kilometer extended danger zone on the southeast sector must be exercised due to the increased possibilities of sudden and hazardous phreatic eruptions,” Phivolcs said.

Likewise, Phivolcs asked civil aviation authorities to advise pilots to avoid flying close to the volcano’s summit as ash from any sudden phreatic eruption can be hazardous to aircraft.

“People living within valleys and along river/stream channels especially on the southeast, southwest and northwest sector of the edifice should be vigilant against sediment-laden stream flows and lahars in the event of heavy and prolonged rainfall should phreatic eruption occur,” it also said.