The Philippine Institute of Volcanology and Seismology (Phivolcs) raised Sunday afternoon the alert status on Mayon Volcano to Alert Level 4 out of a maximum of five alert levels—meaning that a major eruption is possible within days.

“This means that a hazardous explosive eruption is possible within days. Thus, areas expected to be affected by such eruption will be accordingly extended,” Phivolcs said in its Bulletin no. 7 of Mt. Mayon issued at 2:30 p.m.

Phivolcs said that to ensure the safety of the public, it is recommending an Extended Danger Zone from the summit of eight kilometers at the southern sector and seven kilometers at the northern sector of the restive volcano in Albay province.

“Areas just outside of this Extended Danger Zone should prepare for evacuation in the event explosive eruptions intensify,” Phivolcs warned.

Alert level 4 means a volcano is exhibiting low-frequency quakes, intense crater glow and lava fragments in the summit.

Earlier Sunday, meteorologists said a potential storm is threatening to hit the southern part of the country and bring heavy rains to Albay.

The state-run Philippine Atmospheric, Geophysical and Astronomical Services Administration said heavy rain in the area could trigger dangerous ‘lahar’ flow from the slopes of Mayon Volcano.

PAGASA Director Prisco Nilo said they are monitoring the development of the low-pressure area —a rain-inducing weather system—located some 3,000 kilometers east of northern Mindanao Sunday.

Nilo said the LPA, in case it develops into a storm, could threaten the Visayas and northern Mindanao and could help intensify the northeast monsoon locally known as “amihan” and bring rains to Albay.

“Lalakas ang ulan sa Albay kung tatama ng Visayas ang bagyo,” Nilo told the Manila Bulletin when asked whether Albay would be affected by the potential storm.

PAGASA weather forecaster Connie Rose Dadivas said the LPA might enter the Philippine Area of Responsibility after Christmas Day.

Records show that storms in December could be deadly, particularly for the Bicol region.

In December 2006, heavy rains from typhoon “Reming” (international name: Durian) caused landslides and floods at the base of Mayon Volcano, resulting in the deaths of 1,266 people.

Mt. Mayon erupted in August of the same year, resulting to the evacuation of 48,000 people, and depositing huge pyroclastic materials in its slopes that cascaded as lahar when Reming struck.

However, Robert Sawi, chief of PAGASA's weather forecasting section, said the LPA might have a slim chance of hitting the Philippines which was already visited by 22 typhoons in 2009, including “Ondoy” and “Pepeng” which submerged large areas in Luzon during the last quarter.

“May nakikita tayo sa Pacific na possible formation pero malabo pang pumasok dahil may kalamigan na ang panahon at kung mag-develop man ito (into a storm) ay baka matunaw din,” Sawi told the Bulletin.

Dadivas said that hopefully, a frontal system near the LPA would affect its direction and pull it away from the Philippines. Phivolcs said Mt. Mayon continued to exhibit a high level of activity.

“A total of 222 volcanic quakes and tremors were recorded by the seismic network. One of these events was an explosion-type earthquake that produced a dirty white to grayish ash column that reached a maximum height of about 500 meters above the summit before drifting southwest,” according to a Phivolcs 24-hour observation report for Dec. 19 that ended at 7 a.m. Sunday.Harmonic tremors were continuously recorded by the seismic instruments, Phivolcs said.

“During a cloud break this morning, steaming activity ranged from dirty white to light brown in color. Night observation still showed intensified crater glow and continuous rolling down of incandescent materials from the crater,” the report added.

On the other hand, advancing lava flow from Mayon has now reached approximately 4.5 kilometers downslope from the crater along the Bonga-Buyuan Gully. Sulfur dioxide emission also increased from 2,034 tons per day to 7,024 tons per day.