No casualties were reported.
Mount Sinabung in North Sumatra province was shooting smoke and ash as high as 1000 metres into the air and hot ash clouds were blowing three kilometres to the southeast, Indonesia’s Volcanology and Geological Hazard Mitigation Centre said.
There were no casualties from the eruption, said Armen Putra, an official at the Sinabung monitoring post.
He said villagers were advised to stay five kilometres from the crater’s mouth and should be aware of the peril of lava.
An alert has been maintained at the second-highest level while authorities closely monitor the volcano after sensors picked up increasing activity in recent weeks.
The 2600-metre mountain has been rumbling since last year.
It sent volcanic materials more than 5000 metres into the sky and deposited ash on nearby villages when it erupted early this month.
About 30,000 people have been forced to leave their homes around Sinabung in the past few years.
Sinabung was dormant for four centuries before erupting in 2010, killing two people.
Another eruption in 2014 killed 17 people, while seven died in a 2016 eruption.
The volcano, one of two currently erupting in Indonesia, has sporadically come to life since then.
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.