Officials in Indonesia issued a red alert on Monday, warning that the nation's most active volcano may be about to erupt.
Thousands of people have been ordered to evacuate a 10km ring around Mt Merapi, near the city of Yogyakarta in central Java.
Merapi is one of the world's most volatile volcanoes and has become increasingly active, sending up clouds of white smoke.
Officials say earthquakes over the past week have pushed up molten rock, which is now just 1km below the crater, the ABC reports.
Emergency shelters are being prepared for an influx of evacuees. However, many of those in the evacuation zone are concerned about leaving livestock and crops unattended and they have been reluctant to move.
Two people were killed when Mt Merapi last erupted in 2006. The worst death toll was in 1930 when 1300 people died.
