Perbakti-Gagak

The Perbakti-Gagak volcanic complex, also known as Kiaraberes-Gagak, is a cluster of deeply eroded stratovolcanoes situated immediately SW of Salak volcano. The summit ridge of Gunung Perbakti is elongated in a NW-SE direction, and Gunung Endut volcano rises above a saddle to its SW. Gunung Gagak, to the NW, is capped by pumice and obsidian, with obsidian lava flows extending N and NE. Quaternary rhyolitic lava domes form a NNE-trending chain at the eastern side of the complex. Two 2-km-wide depressions on the northern and southern sides of Perbakti form the headwaters of the Kaluwung Herang and Pamatutan rivers, respectively. The complex is marked by vigorous geothermal activity. Fumaroles, mud pots, and hot springs are located on the S and SE flanks of Perbakti and at the Kiaraberes area, which includes the commercial geothermal field of Awibengkok. Mild phreatic eruptions took place during the Holocene into historical time from flank fumarolic fields.