HVO scientists measure volcanic gasses—Kīlauea caldera floor, July 22
HVO scientists walk transects along the down-dropped portion of Kīlauea caldera floor as part of a gas survey conducted on July 22. The multigas instruments carried on the scientists' backs measure the amount of carbon dioxide (CO2), sulfur dioxide (SO2), water vapor (H2O), and hydrogen sulfide (H2S) via an inlet hose oriented toward the ground surface. These measurements will provide a map showing areas of the caldera floor where specific volcanic gases are being emitted and their concentrations. The light-colored ground the scientists are walking on is evidence of such gases interacting with, and altering, the darker volcanic rocks in the area. USGS image by K. Mulliken.