Merapi, 2,963 meters (9,721 feet) high, is one of Indonesia’s most active volcanoes and is already at the country’s second highest alert level.
Kasbani, head of Indonesia’s geological and volcanology hazard mitigation center, said Merapi has spewed “rather intense” hot clouds at least 30 times since Wednesday morning and warned of the danger of lava cutting roads near the volcano.
Photographs shared on social media showed ashes covering the homes of some nearby residents.
There were no immediate reports of damage, but some residents have chosen to leave their homes, said the local disaster mitigation agency.
Located in the so-called “Circle of Fire”, Indonesia has more volcanoes than any other country and Merapi erupted violently in 2010, killing more than 350 people.
The eruption comes just weeks after a magnitude 6.2 earthquake on the island of Sulawesi, Indonesia, destroyed buildings and left dozens dead.