Legazpi City – The Philippine Institute of Volcanology and Seismology (Phivolcs) raised Alert Level 4 over Mayon volcano after it belched out a 10-kilometer high ash column at 12:45 p.m. on Monday.

On a bulletin issued at 1 p.m., Phivolcs raised the alert level from 3 (increased tendency to hazardous eruption) to 4 (hazardous eruption imminent).

Phivolcs volcanologist Paul Alanis said eruption “may happen in hours.”

“The danger zone is extended to 8 kilometers all around the volcano,” Phivolcs chief Renato Solidum said in a phone interview. Evacuation of residents within the additional kilometer radius was immediately instigated by local government units.

The volcano had started showing increased activity or unrest since January 14.