Indonesian authorities raised the alert for the volatile Mount Merapi volcano on the densely populated island of Java and ordered people within 3 kilometers (2 miles) to evacuate.
Merapi has erupted four times since Monday, sending out a 3,500 meter (11,483 feet) column of volcanic material and dusting the surrounding region in ash.
Sutopo Purwo Nugroho, the national disaster mitigation agency’s spokesman, said some 660 people living within the exclusion zone have evacuated since early Tuesday.
Indonesia’s geological agency raised Merapi’s alert from normal to “beware,” because of its increased activity.
There have been no reports of casualties and operations at Adi Sucipto airport in Yogyakarta have not been affected.
The 2,968-meter (9,737-foot) mountain is about 30 kilometers (18 miles) from the Yogyakarta city center. About a quarter million people live within a 10 kilometer radius of the volcano, according to figures from authorities in surrounding districts. Its last major eruption in 2010 killed 347 people and caused the evacuation of 20,000 villagers.
Nugroho said climbing on Merapi is prohibited and only disaster agency personnel or related researchers should enter the restricted area.
Indonesia, an archipelago of more than 250 million people, sits on the Pacific “Ring of Fire” and is prone to earthquakes and volcanic eruptions. Indonesian government seismologists monitor more than 120 active volcanoes.