Thousands of people were forced to evacuate Sunday after a Philippine volcanic eruption spewed ash and toxic gases posing serious health risks.

Seismology researchers said they had recorded at least one volcanic earthquake in the past 24 hours and red-hot rocks were falling from Mt. Mayon in the central province of Albay.

More than 12,800 people have been moved to evacuation centers, the Philippine civil defense office said, most from farming villages at or near the foot of the volcano.

"We're away from our home, but it's still better here because it's too dangerous," mother-of-two Rachel Ramirez, 30, told AFP during her third day at a school near the town of Daraga that had been turned into an emergency shelter.

Mayon, about 330 kilometers (205 miles) southeast of the capital Manila, is considered one of the most volatile of the country's 24 active volcanoes.

The Philippine Institute of Volcanology and Seismology said rocks were falling from a disintegrating lava dome being pushed out of the crater by molten material below the earth.

The rocks were raining down on areas up to 2 kilometers away and sulfur dioxide emissions had tripled Saturday, state volcanologists said.

"There is a concomitant health risk while being close to the eruption because of inhaling sulfur dioxide gas or the particulate matter of ashfalls," Health Secretary Teodoro Herbosa told a press briefing Sunday.

On Thursday a five-step alert system for the volcano had been raised from two to three.

"With Albay in a state of calamity due to Mayon's activity, we remind people to follow the recommendations and evacuation instructions of your local governments," Philippine President Ferdinand Marcos said Saturday.

Earthquakes and volcanic activity are common in the Philippines due to their position on the Pacific "Ring of Fire" where tectonic plates collide.

Five years ago, Mayon displaced tens of thousands of people after spewing millions of tons of ash, rocks and lava.

The country's most powerful eruption in recent decades was Mount Pinatubo in 1991 which killed more than 800 people.

That disaster produced an ash cloud that traveled thousands of kilometers.

Mayon lies in a region also hit by many of the roughly 20 typhoons or tropical storms to strike the Philippines each year.

The frequent weather disasters often kill people, ravage farms, and help to keep millions poor.