Mount Merapi in Indonesia's Central Java province on Sunday afernoon spewed another searing cloud of ash down its slopes after a lull in activity.

Monitoring official Subandrio said the new blast came after thousands of people who had fled the area rushed back to check on their homes. Their fate is still unclear.

Mount Merapi began erupting on Tuesday, forcing more than 40, 000 to evacuate. The blasts have so far killed 38 people, local reports said.

Indonesia lies on the Pacific Ring of Fire, a series of fault lines in the earth's surface that is prone to earthquakes and volcanic eruptions.