Sibualbuali is an eroded Pleistocene stratovolcano with two solfatara fields on the eastern flank. Rhyolitic-dacitic lava domes erupted from fissure vents along the Toru-Asik fault to the S are late Pleistocene or possibly Holocene in age, and are considered part of the Sibualbuali volcanic center (Aspden et al., 1982).