Eruption pause provides an opportunity to probe volcanic pollution

Only small amounts of sulfur dioxide (SO2) and hydrogen sulfide (H2S) are currently being released from Kīlauea, but they chemically react with each other (oxidation-reduction reaction) to form the bright yellow sulfur deposits visible on the crater walls within Halema‘uma‘u. The current low sulfur emission rates at Kīlauea have contributed to beautifully clear skies in downwind areas. USGS photo by M. Poland, 03/22/2019.