Fumaroles are active at the bottom of the inner crater, with about five separate fumarole areas identified within the crater before the 2006 eruption. In 1997, a gas cloud from the fumaroles filled the entire caldera during the nights. Fumarolic activity and degassing is limited to the crater; there is no evidence of such gas exhalations elsewhere on the volcano. Ubinas is a major source of volcanic carbon dioxide and sulfur dioxide in the atmosphere of Earth, producing SO2 at a rate of about . Reportedly, the sound of the fumaroles can be heard from the village of Ubinas.