The Philippines raised the alert for the Mayon volcano early Sunday, citing signs of rising magma.
The level of danger was etched-up a notch following concerns that the phreatic or steam-driven eruptions could lead to hazardous emissions.
“The public is strongly advised to be vigilant and desist from entering the six-kilometer radius Permanent Danger Zone to minimize risks from sudden explosions, rockfall and landslides,” Philippine Institute of Volcanology and Seismology (Phivolcs) warned.
Phivolcs said the first "steam-driven eruption" started at about 5:00 p.m. local time, recording an ash column of 2500m high. The Level 2 alert suggests that the current activity is “probably of magmatic origin, which could lead to more phreatic eruptions or eventually to hazardous magmatic eruptions.”
A phreatic eruption occurs when magma heats ground or surface water, resulting in steam rising into the sky.
Saturday’s eruption unleashed ash, rocks and sulfuric odor, and was followed by rumbling sounds and a faint glow in the crater, according to Phivolcs.
"The public is strongly advised to be vigilant and desist from entering the 6k-radius Permanent Danger Zone to minimise risks from sudden explosions, rockfall and landslides," Phivolcs said.
A second ash eruption was also recorded before noon on Sunday.
“We have not reached the critical level,” head of the Albay Provincial Disaster Risk Reduction and Management Office, Cedric Daep, insists in a radio interview.
“Alert level 3 is what we considered critical, 4 is when eruption is imminent, and 5 is eruption in progress,” he said, adding that people in evacuation centers may be allowed to return homes if Phivolcs does not raise the level.
Phivolcs chief Renato Solidum said the volcano appeared due for another eruption.
Residents were evacuated from two villages near the volcano on Saturday. The institute advised people near ashfall to cover their noses and mouths with a damp, clean cloth or dust mask.
Mayon’s most destructive eruption was in February 1841, when lava flows buried a town and killed 1,200 people.
It last erupted in 2014, spewing lava and forcing thousands of people to evacuate.
The volcano has been displaying abnormal behavior since late last year.