MANILA, Sept. 8 (Xinhua) -- The Philippines raised on Thursday the alert level for the Mayon Volcano, indicating that the volcano is exhibiting "abnormal" signs that may trigger rockfalls and avalanches.
"Phivolcs is now raising the alert statues of (Mt.) Mayon from alert level 0 to 1. This means that is at an abnormal condition and has entered a period of unrest," the institute said in its bulletin.
But the institute said that "no crater glow has been observed so far."
Nevertheless, it warned the public, including local and foreign tourists, "to avoid entry in the six-kilometer permanent danger zone due to perennial hazards of rockfalls, avalanches, ash puffs and sudden steam-driven or phreatic eruption at the summit area which may occur without warning."
The Philippine Institute of Volcanology and Seismology said in a statement that it has noticed an increase in sulphur dioxide gas emission, ground deformation and volcanic earthquake activity around the volcano.
The institute also said that it has recorded an "earthquake swarm" of 146 earthquakes from Aug. 3 to 6, adding that steaming activity from the crater has ranged "from weak to moderate."
Mt. Mayon, one of the Philippine most active volcano famous for its beauty and near-perfect symmetry, is located in Albay province, about 300 km southeast of the Philippines capital Manila. It has an elevation of 2,462 meters.
It erupted in November 2009, according to the institute records.
In an 1814 eruption, more than 1,200 people were killed and three towns were buried under mud and rock.
Tourists often flock to the Albay province to witness glowing orange and red lava flowing out of the volcano's crater. Enditem