Dieng Volcano complex is located near Wonosobo, Central Java, Indonesia. For several centuries volcanic activity at Dieng has been dominated by phreatic eruptions, and geothermal activity (fumaroles, solfataras, mud pools, hot springs). The volcano is composed of two strato volcanoes (Butak Petarangan and Dieng) and many craters. Warm acidic lakes fill some of the craters. Volcanic cones at Dieng include the following - Bismo, Srojo, Binem, Pangonan, Merdodo, Pagerkandang, Nogosari, Petarangan, Telogo Dringo, Pakuwaja,Kendil, Kunir and Prambanan.
Dieng Volcano is noted for the release of carbon dioxide, which sometimes results in fatalities to residents as it happened on 20 February 1979 when 149 died after inhaling poisonous gas from the eruption of its Timbang Crater. Fumarole areas include Kawah (crater) Sikidang, Kawah Sigajah, Kawah Kumbang, Kawah Sibanteng, Kawah Upas,Telogo Terus, Kawah Pagerkandang, Kawah Sipandu, Kawah Siglagah and Kawah Sileri. Butak Petarangan is the second highest volcano located in the Dieng complex. It consists of a crater-lake named Telogo Dringo and Condrodimuko Fumarole Field. Sileri Crater which is the most active had its last phreatic eruption in July 2003.
The morphology of the area is mostly hilly, with gradients in the range of 10-40 degrees. It lies 1900-2000 meters above sea level. The lithology mostly consists of piroclastic deposits. The plastic soil is reddish brown in color and the grain size of the soil is silt-clay with thicknesses between 1-3 meters. The Sibanteng Crater landslide was triggered by the lithology, morphology and the water condition of the area. Heavy rain occurred during 3 days prior to the landslide. Based on observation, the poisonous gas concentration is still below the allowed limits.
Based on visual and data analysis, on Thursday 22th January 2009 at 4:00 pm, Dieng Volcano's status decreased from level II to level I (Normal). Howevere there is still potential for phreatic eruptions, and general awareness must take this into account, especially during heavy rains which could trigger more landslides.
Resource : Report from Geology Agency, Republic of Indonesia
Kawah Sibanteng before eruption (source image : Virtual Tourist)