Highest levels of volcanic sulfur dioxide emission recorded at the volcano which indicates possible eruption.
Indonesia’s most volatile volcano has erupted on the densely populated island of Java, spewing smoke and ash high into the air and sending streams of lava and gasses down its slopes.
Mount Merapi unleashed clouds of hot ash at least seven times on Sunday, as well as a series of fast-moving pyroclastic flows – a mixture of rock, debris, lava and gasses – said Hanik Humaida, who heads the city of Yogyakarta’s Volcanology and Geological Hazard Mitigation Center.
The rumbling sound could be heard several kilometres away. No casualties have been reported.
The mountain has seen increased volcanic activity in recent weeks, with its lava dome growing rapidly before partially collapsing on Sunday, sending rocks and ash flowing down the volcano’s southwest flank, Humaida added.
Ash from the eruption blanketed several villages and nearby towns, she said.
Villagers living on Merapi’s fertile slopes were advised to stay 5km (3.1 miles) away from the crater’s mouth and should be aware of the danger posed by lava, Indonesia’s Geology and Volcanology Research Agency said.
Mount Merapi is the most active of more than 120 active volcanoes in Indonesia and has repeatedly erupted with lava and gas clouds recently.
Merapi’s last major eruption in 2010 killed about 350 people.
The 2,968m (9,737 feet) peak is near Yogyakarta, an ancient city of several hundred thousand people embedded in a large metro area. The city is also a centre of Javanese culture and a seat of royal dynasties going back centuries.
This latest eruption sent hot ash 1,000m (3,280 feet) into the sky, and the searing clouds of gas travelled up to 3km (1.8 miles) down its slopes several times, the country’s geology agency said on its website.
The Volcanology and Geological Hazard Mitigation Center did not raise Merapi’s alert status, which already was at the second highest of four levels since it began erupting last November.
Indonesia, an archipelago of 270 million people, is prone to earthquakes and volcanic activity because it sits along the Pacific “Ring of Fire,” a horseshoe-shaped series of seismic fault lines around the ocean.