Average measurements of SO2 from Kilauea summit in the past month

Sulfur dioxide (SO₂) emission rates measured using an upward-looking ultraviolet spectrometer. These data are collected by traversing the gas plume in a vehicle or helicopter, downwind of Halema‘uma‘u, generally within and/or southwest of Kīlauea caldera. Results from multiple traverses during a day are averaged to yield the emission rates shown here. Successful measurements depend on wind, weather, and staff availability. Values are preliminary and are subject to revision.