MANILA, Nov 11, 2009 (AFP) - One of the Philippine's most active volcanoes shot plumes of ash into the air early Wednesday, officials said, warning local residents they would have to evacuate in case of an eruption.
A pre-dawn explosion at the Mayon volcano covered nine nearby villages, home to about 22,000 people, with a thin carpet of grey ash, the Philippine Institute of Volcanology and Seismology said.
In a sign an eruption could be imminent, the area around the cone-shaped volcano rumbled and shook for about three minutes, with rock fragments on the upper slopes glowing red, the institute added in its latest bulletin.
The volcano, which lies southeast of the capital Manila, remains at alert level 2, defined as "a state of unrest which could lead to more ash explosion or eventually to hazardous magmatic eruption," the bulletin said.
Residents have been urged to steer clear of the crater area, and if the alert level goes up, a preemptive evacuation of the surrounding villages will be undertaken, a government advisory said.
"In case of ash fall, residents in affected areas should stay indoor or cover their nose with clean wet cloth or dust mask," it added.
Mayon, which is also a major tourist attraction, has erupted 48 times since records began, most recently in 2006. According to government seismologists, it has shown abnormal activity since July this year.
Its perfect cone rises 2,460 metres (8,070 feet) over the half-submerged belfry of the town of Cagsawa, which was buried in a deadly 1814 eruption.