The Mount Merapi volcano on Indonesia’s Java island spewed searing ash and other volcanic debris that poured up to 1.
5 kilometres down its slopes on Wednesday, the country’s geological agency said.
Pyroclastic flows – a fast-moving mixture of extremely hot rock fragments, gas, and ash – blasted from the volcano for four hours in the early morning, according to the Research and Development Center for Geological Disaster Technology, which monitors the volcano.
There were no reports of casualties and the alert level remained at the second-highest level, it said.
Hundreds of residents fled their homes near the volcano to safer locations after recent eruptions, but many have since returned.
Local authorities said they were prepared to evacuate residents in the event of major eruptions.
“We are taking inventory of vehicles that will be used to transport villagers,” the head of the local civil protection agency, Makwan, was quoted as saying by the Antara news agency.
“So far no ash rain has been observed in residential areas,” he said.
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.