Merapi is one of Indonesia’s most dangerous volcanoes.
The 2010 eruption released poisonous gases and a rain of ash that fell on an area that is home to millions of people.
The danger now is from the accumulated ash on the summit and flanks of Merapi that could mix with torrential rain and flow down mountain streambeds with catastrophic force.
Hundreds of workers collect sand each day for use in cement production.
They and others have been warned to stay away from Merapi's mountain streams until the danger subsides.
Photo: Fakhri Anindita