Indonesia volcano: Mount Merapi erupts sending giant ash cloud into sky

Authorities order residents to evacuate as crater spews out sand and pyroclastic material

Indonesia's most active volcano has erupted, sending a giant ash column 18,000 ft into the sky and forcing families living nearby to evacuate their homes.

Mount Merapi's sudden eruption on Friday morning was accompanied by a rumbling sound with medium to strong pressure, Disaster Mitigation Agency spokesperson Sutopo Purwo Nugroho said.

People living within three miles of the crater fled as the volcano spewed out sand and pyroclastic material, with many heading to barracks set up for the displaced.

There were no immediate reports of casualties.

Mr Nugroho said an airport in the nearby city of Yogyakarta was forced to close for around an hour due to the spread of volcanic ash, and that 120 hikers on Merapi were safe.

The eruption, however, did not raise the alert status of the volcano, which is at a normal level with no eruption expected in the foreseeable future.

The 2,968-metre (9,737 ft) mountain between Yogyakarta and Central Java provinces is the most active of 500 Indonesian volcanoes. Its last major eruption in 2010 killed 347 people and caused the evacuation of 20,000 villagers.

Indonesia, an archipelago of more than 250 million people, is prone to earthquakes and volcanic activity because it sits along the Pacific "Ring of Fire," a horseshoe-shaped series of fault lines.

Additional reporting by AP