Indonesia's Mount Merapi, one of the world's most active volcanoes, has spewed a plume of grey ash into the sky as fiery red molten lava streamed down from its crater.
Authorities did not raise the rumbling volcano's alert status after the eruption on Thursday evening.
But any activity at Merapi raises concern and local residents have previously been ordered to stay outside a five-kilometre (three-mile) no-go zone around the crater near Indonesia's cultural capital Yogyakarta.
Its last major eruption in 2010 killed more than 300 people and forced some 280,000 others to evacuate.
It was Merapi's most powerful eruption since 1930, which killed some 1,300 people, while another explosion in 1994 took about 60 lives.
Across the Southeast Asian archipelago, Mount Karangetang on Sulawesi island also erupted this week with more than a hundred nearby residents ordered to evacuate from the remote site.
Indonesia has more than 17,000 islands and islets -- and nearly 130 active volcanoes.
It sits on the Pacific "Ring of Fire", a vast zone of geological instability where the collision of tectonic plates causes frequent quakes and major volcanic activity.