The Philippines' most active volcano has shown signs of imminent eruption, forcing thousands of people on the main island of Luzon to evacuate.
Authorities upgraded the alert level at the Mayon volcano in the southern part of Luzon to "level 3" Sunday after observing steam eruptions and a bright lava glow.
Alert level raised following steam eruptions and rockfalls on Mayon volcano
Hundreds of families have been moved from neighborhoods at base of volcano
As many as 3,000 villagers fled their homes while the volcano spewed ash, according to CNN affiliate CNN Philippines.
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) issued the alert indicating an "increased tendency towards hazardous eruption" after three steam-driven eruptions and dozens of rockfalls on Sunday afternoon.
The volcano is "exhibiting relatively high unrest," the agency said in a tweet on Sunday, adding that "hazardous eruption is possible within weeks or even days."
A "bright crater glow" at the summit crater indicates "the growth of a new lava dome and beginnings of lava flow towards the southern slopes," the agency said.
The agency recommended creating an 11 km (7 mile) danger zone around the volcano to mitigate against "rockfalls, landslides and sudden explosions or dome collapse."
The tweet also advised pilots not to fly near the summit, since ash could be hazardous to aircraft.
The last time Mayon erupted the volcano exhibited similar activity beforehand, PHIVOLCS Director Renato Solidum told CNN Philippines.
Over the weekend, authorities ordered the evacuation of areas at the foot of the volcano. More than 900 families from 16 neighborhoods in the vicinity of the volcano were moved to shelters in neighboring towns, CNN Philippines quoted the National Disaster Risk Reduction and Coordinating Council (NDRRMC) as reporting.
However, Solidum added that the activity so far may not lead to an explosive eruption.
"Sometimes this eruption activity need not really result (in) very explosive eruptions. Sometimes it would result (in) non-explosive eruptions where lava would ooze out of the crater, but not explode," Solidum said.
Situated on the island of Luzon, about 330 kilometers (205 miles) southeast of Manila, Mayon is one of the world's most active volcanoes.
Since 1616, the imposing stratovolcano has erupted 47 times, with many of the explosions causing deadly mudflows and ash falls.
In 2014, thousands of residents were ordered to evacuate the same area after a "critical" alert was issued, while in 2013, five climbers died when they were hit by falling rocks thrown up by a particularly violent blast.
The volcano's most devastating eruption took place in 1814, killing at least 1,200 people.
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