More than 30,000 people living along the volcano’s fertile slopes have been evacuated to refugee camps, mosques and churches in nearby villages.
Vulcanologists fear that a much more destructive explosion could occur in the coming weeks or months.
But they also say it’s possible Sinabung will go back to sleep after letting off steam.
Torrential rains accompanying the eruption have washed large quantities of ash and mud down the volcano’s slopes, inundating abandoned homes.
Sinabung's awakening caught scientists off guard. Local vulcanologists failed to notice signs of rising magma, slight uplifts in land and minor volcanic tremors.
Some archaeologists believe an eruption of a prehistoric volcano near Mount Sinabung nearly wiped out the human race when it erupted 69,000-77,000 years ago.
Photo: Meteorological And Geophysical Agency (Indonesia)