The Mount Merapi volcano on Indonesia’s Java island spewed hot clouds down its slopes on Thursday, the country’s geological disaster agency said.
The pyroclastic flow – a fast-moving mixture of extremely hot rock fragments, gas and ash – travelled two kilometres down to a nearby river, said the Research and Development Centre for Geological Disaster Technology, which monitors the volcano.
There were no reports of casualties.
More than 100 residents living near the mountain were transferred to temporary shelters after a series of similar eruptions on Wednesday, said the head of the local civil protection agency, Makwan.
Hundreds of residents fled their homes near the volcano to safer locations after recent eruptions, but many have since returned.
Indonesia sits on the Pacific Ring of Fire, an area known for seismic upheavals and has about 128 active volcanoes.
The 2,968-metre-high Mount Merapi has erupted several times since 2018.
Its last deadly eruption was in 2010, when more than 340 people were killed and over 60,000 more displaced.
It is the most active of Indonesia’s 127 volcanoes.