MEDAN, Indonesia -- A volcano in western Indonesia erupted again Sunday, unleashing volcanic ash high into the sky and forcing the evacuation of villagers living around its slope.

Officials raised Mount Sinabung's alert status to the second-highest level after the8,530-foot-high mountain erupted early Sunday, said National Disaster Mitigation Agency spokesman Sutopo Purwo Nugroho.

Authorities were working to evacuate residents from four North Sumatra province villages located within the mountain's three-kilometre danger zone, Nugroho said. About 1,300 villagers have been relocated to safer areas so far.

It was the volcano's second big eruption since late last month, with its Oct. 24 explosion prompting the evacuation of more than 3,300 people.

In September, more than 15,000 people were forced to flee when Mount Sinabung rumbled to life after being dormant for three years.

The volcano's previous major eruption, in August 2010, killed two people and forced 30,000 others to flee. It caught many scientists off guard because it had been quiet for four centuries.

Mount Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific Basin.