Using Drones and Miniaturized Instrumentation to Study Degassing at Turrialba and Masaya Volcanoes, Central America

Abstract

Gas measurements using unmanned aerial vehicles, or drones, were undertaken at Turrialbavolcano, Costa Rica, and Masaya volcano, Nicaragua, in 2016 and 2017. These two volcanoes are thelargest time-integrated sources of gas in the Central American Volcanic Arc, and both systems are currentlyextremely active with potential for sudden destabilization. We employed a series of miniaturizeddrone-mounted instrumentation including a mini-DOAS, two MultiGAS instruments, and an optical particlecounter, supplemented by ground-based measurements. Payloads were typically 1–1.5 kg andflight timeswere 10–15 min. The measurements were both accurate and precise due to the inherent sensitivity of theinstrumentation and the high gas concentrations, which the drones were able to sample. The quality ofdata obtained by our drones was comparable to that obtained by our ground-based measurements. AtTurrialba in April 2017, we measured an average SO2flux of 1,380 ± 280 T/day, CO2/SO2of 6.5, and H2O/SO2of 27.8. Using these values, we calculated a CO2flux of 6,170 T/day and an H2Oflux of 10,790 T/day. At Masayain May 2017, the average SO2flux was 1,560 ± 180 T/day, with CO2/SO2of 3.9 and H2O/SO2of 62.3, givinga mean CO2flux of 4,150 T/day and mean H2Oflux of 27,330 T/day. The elevated carbon and waterfluxes andratios are indicative of underlying magmas that are enriched in these components, resulting in the high levelsof activity observed.