Modest volcanic SO2 emissions from the Indonesian archipelago.

Indonesia hosts the largest number of active volcanoes, several of which are renowned for climate-changing historical eruptions. This pedigree might suggest a substantial fraction of global volcanic sulfur emissions from Indonesia and are intrinsically driven by sulfur-rich magmas. However, a paucity of observations has hampered evaluation of these points—many volcanoes have hitherto not been subject to emissions measurements. Here we report new gas measurements from Indonesian volcanoes. The combined SO₂ output amounts to 1.15 ± 0.48 Tg/yr. We estimate an additional time-averaged SO₂ yield of 0.12-0.54 Tg/yr for explosive eruptions, indicating a total SO₂ inventory of 1.27-1.69 Tg/yr for Indonesian. This is comparatively modest—individual volcanoes such as Etna have sustained higher fluxes. To understand this paradox, we compare the geodynamic, petrologic, magma dynamical and shallow magmatic-hydrothermal processes that influence the sulfur transfer to the atmosphere. Results reinforce the idea that sulfur-rich eruptions reflect long-term accumulation of volatiles in the reservoirs. Indonesia is the country with the most active volcanoes, several of which are renowned for climate-changing eruptions. Here the authors show a rather moderate sulfur emissions budget and reinforce the idea that sulfur-rich eruptions reflect long-term accumulation of volatiles in the reservoirs. [ABSTRACT FROM AUTHOR]