Degassing at Sabancaya volcano measured by UV cameras and the NOVAC network

Abstract

We used low-cost Raspberry Pi ultraviolet (UV) cameras to measure sulphur dioxide (SO2) fluxes from Sabancaya volcano, Peru, during eruptive activity on 27 April 2018. Light dilution corrections were made by operating instruments at two distances simultaneously. Estimated SO2 fluxes of 27:1 kgs-1 are higher than previously reported, likely due to the current eruptive episode (ongoing since November 2016). Each eruptive event included frequent (2-3 per minute), ash-rich emissions, forming gas pulses with masses of 3.0-8.2 tonnes SO2. Sustained degassing and lack of overpressure suggest open-vent activity. Mean fluxes are consistent with those measured by a permanent NOVAC station (25:9 kgs-1) located under the plume, with remaining differences likely due to windspeed estimates and sampling rate. Our work highlights the importance of accurate light dilution and windspeed modelling in SO2 retrievals and suggests that co-location of UV cameras with permanent scanning spectrometers may be valuable in providing accurate windspeeds.