The lava dome in the main crater of Olca is fumarolically active, with the activity occurring over a long elliptical fumarole field. Paruma volcano also shows fumarolic activity. Additional reports claim that vapours emanate from yellow pits on the western side. The fumarolic activity at Olca-Paruma forms clouds that are visible over large distances. Measurements have yielded sulfur dioxide concentrations of 35 ppm over the area.