Locals located within 3 miles from the eruption have had to flee, evading ashes, hot sand and pyroclastic material from the volcano, with many heading to barracks set up for the displaced.
Residents in Yogyakarta, a city of 2.4 million located 17 miles to the south of the volcano are not believed to be in danger.
The eruption, however, has not raised the alert status of the volcano, which remains at the normal level, with no eruption expected in the near future.
Gunung Merapi (Fire mountain in Indonesian) is a 2,968-meter (9,737 ft) volcano on Java and the most active of the Indonesian archipelago's 500 volcanos. In 2010, an eruption of the volcano killed 347 people and forced thousands to leave their villages.