Mount Merapi, one of the country's most active volcanoes, has churned out ash, lava, and gas on the main island of Java, killing at least 28 people. Most were burned to death by bursts of hot air.
The eruption happened less than 24 hours after a tsunami several hundred miles away hit Indonesian islands off Sumatra, triggered by a powerful earthquake.
Indonesian rescue teams are battling to reach an estimated 400 people believed to be missing since the tsunami struck the small islands off the coast of Sumatra.
Officials say a 3m-high wave crashed into the Mentawai islands after a quake on Monday, killing at least 154 people.
Sources and more info available at:
BBC News report - Tsunami for reports, pictures, maps and video
BBC News Report - Volcanic eruption for reports, pictures, maps and video