Powerful bursts of hot ash and gravel erupted from the rumbling volcano in western Indonesia at 1.43 a.m., but the height of the ash could not be seen as it was covered by clouds, said Sutopo Purwo Nugroho, spokesman of the national disaster management agency.
The eruption did not trigger evacuation, but all residents in three villages near the volcano are prepared for displacement, he told Xinhua by phone.
Mount Sinabung in Karo district last erupted June 29 after erupting on and off from September 2013 to February 2014, which left 15 people dead and more than 30,000 others internally displaced.
Mount Sinabung is among the more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the "Pacific Ring of Fire".
The volcano rumbled back in September 2013 after being dormant for 400 years. The Indonesian transport ministry warned aircraft to stay away from the path near the volcano.