Seismicity increased in late June and early July. Earthquakes of M ~2 were felt locally three times on 2 July, and once on 4 July. An emission plume of white, moderately thick steam without ash issued from Sileri crater under low pressure to a height of 50 m. There was a moderate smell of sulfur. The crater lake water was clear to gray in color with temperatures varying between 54 and 94°C.

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.

Information Contacts: R. Sukhyar, Director, Volcanological Survey of Indonesia (VSI), Bandung, Indonesia (URL: http://www.vsi.esdm.go.id/).