CVGHM reported that on 15 January two minor phreatic eruptions from Dieng's Sibanteng crater ejected material that fell within a 50 m radius. The ejecta and a landslide dammed up an area of the Kali Putih River. The Alert Level was raised to 2 (on a scale of 1-4) due to increased activity from Dieng and the potential for flash flooding from a dam breach.

Geological Summary. The Dieng plateau in the highlands of central Java is renowned both for the variety of its volcanic scenery and as a sacred area housing Java's oldest Hindu temples, dating back to the 9th century CE. The Dieng Volcanic Complex consists of multiple stratovolcanoes and more than 20 small Pleistocene-to-Holocene craters and cones over a 6 x 14 km area. Prahu stratovolcano was truncated by a large Pleistocene caldera, which was subsequently filled by a series of cones, lava domes, and craters, many containing lakes. Lava flows cover much of the plateau, but observed activity has been restricted to minor phreatic eruptions. Gas emissions are a hazard at several craters and have caused fatalities. There are abundant thermal features and high heat flow across the area.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)