Volcanic plume characteristics determined using an infrared imaging camera

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 (~ 0.5-1 μm bandwidth) imagery to retrieve SO2 and ash slant column densities (g m− 2) and emission rates or fluxes from infrared thermal imagery at close to ambient atmospheric temperatures. The relatively fast sampling (0.1-0.5 Hz) of the multispectral imagery and the fast sampling (~ 1 Hz) 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 < 10 μm and > 10 μm. 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.