MANILA, Philippines — Kanlaon Volcano on Negros Island remains restive after it emitted 4,279 tons of sulfur dioxide in the past 24 hours, according to the Philippine Institute of Volcanology and Seismology.

Phivolcs said five volcanic earthquakes were also recorded around Kanlaon. Plume emission reached 300 meters high and drifted northwest.

The volcano’s edifice remains inflated, state seismologists said.

Alert level 2 is still in effect over Kanlaon and entry into the volcano’s four-kilometer-radius permanent danger zone is strictly prohibited.

Airmen have been notified to avoid flying close to the volcano as any sudden steam-driven or phreatic eruption is hazardous to aircraft.

On July 2, increased seismic activity at Kanlaon was observed after it generated at least 90 volcanic earthquakes.

“The overall monitoring parameters indicate that magmatic processes beneath the volcano may be driving current unrest, causing increased volcanic and seismic activities, persistently high concentrations of volcanic gas emission and swelling of the edifice,” Phivolcs said.