Degassing of CO2, SO2, and H2S associated with the 2009 eruption of Redoubt Volcano, Alaska

► CO2 (up to 9020 t/d) was monitored in the months prior to the Redoubt 2009 eruption. ► The magmatic system degassed primarily as a closed system. ► Magmas were vapor saturated with a C- and S-rich volatile phase. ► Magmas were buffered by a volatile phase with a stable CO2/SO2 ratio of ~ 2.4. ► Primary volatile contents range from 0.9 to 2.1 wt.% CO2 and 0.27-0.56 wt.% S.