Officials have told local villagers to keep at least three miles from the crater’s mouth and to watch out for dangerous lava from the volcano.
The eruption covered villages up to 12 miles from the crater in a thick layer of ash, according to Armen Putra, a worker at the Mount Sinabung observation post.
Some 30,000 people have been forced to leave their homes in recent years.
The volcano, one of two currently erupting in Indonesia, was dormant for four centuries before exploding in 2010, killing two people.
Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the “Ring of Fire”, an arc of volcanoes and fault lines encircling the Pacific Basin.