December 3, 2022 — Measuring volcanic gas emitted by Mauna Loa

A USGS Hawaiian Volcano Observatory gas specialist uses a FTIR spectrometer on the Northeast Rift Zone of Mauna Loa. The FTIR measures the composition of the gases being emitted during the eruption by measuring how the plume absorbs infrared energy. The plume being generated by the ongoing eruption is sulfur-dioxide (SO₂) rich, but also contains water vapor, carbon dioxide, and halogen gases such as HCl and HF. USGS image by M. Patrick.