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Through integration of multiple data streams to monitor volcanic unrest scientists are able to make more robust eruption forecast and to obtain a more holistic interpretation of volcanic systems. We examined gas emission and gas geochemistry and seismic and petrologic data recorded during the 2015 unrest of Cotopaxi (Ecuador) in order to decipher the origin and temporal evolution of this eruption. Identification of families of similar seismic events and the use of seismic amplitude ratios reveals temporal changes in volcanic processes. SO₂ (300 to 24,000 t/d), BrO/SO₂ (5–10 × 10⁻⁵), SO₂/HCl (5.8 ± 4.8 and 6.6 ± 3.0), and CO₂/SO₂ (0.6 to 2.1) measured throughout the eruption indicate a shallow magmatic source. Bulk ash and glass chemistry indicate a homogenous andesitic (SiO₂ wt % = 56.94 ± 0.25) magma having undergone extensive S‐exsolution and degassing during ascent. These data lead us to …