Volcanic plume characteristics determined using an infrared imaging camera

• Published in: Journal of volcanology and geothermal research Vol. 300; pp. 148 - 166
• Main Authors: Lopez, T., Thomas, H.E., Prata, A.J., Amigo, A., Fee, D., Moriano, D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-07-2015
• Subjects: Thermal imaging broadband; Volcanic emissions; Volcanic plumes; Thermal imaging broadband; Volcanic emissions; Volcanic plumes
• ISSN: 0377-0273; 1872-6097
• DOI: 10.1016/j.jvolgeores.2014.12.009

Measurements of volcanic emissions (ash and SO2) from small-sized eruptions at three geographically dispersed volcanoes are presented from a novel, multichannel, uncooled imaging infrared camera. Infrared instruments and cameras have been used previously at volcanoes to study lava bodies and to assess plume dynamics using high temperature sources. Here we use spectrally resolved narrowband (~0.5–1μm bandwidth) imagery to retrieve SO2 and ash slant column densities (gm−2) and emission rates or fluxes from infrared thermal imagery at close to ambient atmospheric temperatures. The relatively fast sampling (0.1–0.5Hz) of the multispectral imagery and the fast sampling (~1Hz) of single channel temperature data permit analysis of some aspects of plume dynamics. Estimations of SO2 and ash mass fluxes, and total slant column densities of SO2 and fine ash in individual small explosions from Stromboli (Italy) and Karymsky (Russia), and total SO2 slant column densities and fluxes from Láscar (Chile) volcanoes, are provided. We evaluate the temporal evolution of fine ash particle sizes in ash-rich explosions at Stromboli and Karymsky and use these observations to infer the presence of at least two distinct fine ash modes, with mean radii of <10μm and >10μm. The camera and techniques detailed here provide a tool to quickly and remotely estimate fluxes of fine ash and SO2 gas and characterize eruption size.
•Multispectral thermal camera deployed at three active volcanoes•Volcanic ash and SO2 emissions quantified by a multispectral infrared camera•Fine ash mass estimated from IR imagery and an a priori particle size distribution•Accurate plume velocities determined from IR imagery and an optical flow model