Indonesian scientists have placed 11 volcanoes under close watch after a series of powerful quakes awoke intense subterranean forces and increased the chances of a major eruption.
Tens of thousands of people have spent a third night in temporary camps after fleeing the slopes of Mount Talang on Sumatra island, where hot ash has been raining down since Monday.
On Wednesday, Anak Krakatau, was put on alert status, amid warnings of poisonous gas emissions.
A similar warning was earlier issued on Tangkuban Perahu, near the west Java island city of Bandung, which will next week host more than 50 heads of state.
Indonesia's Vulcanology Office also says Mount Merapi, 70 kilometres north of the Sumatran city of Padang, has been on alert since last August, but, like others, is now under closer watch. "
Villagers evacuate from the area around the Mt Talang volcano on Indonesia's Sumatra island. [Reuters]