Spatial variations in lava flow field thermal structure and effusion rate derived from very high spatial resolution hyperspectral (MIVIS) data

Abstract

High spatial resolution hyperspectral measurements of volcanic thermal anomalies allow for an unconstrained solution of a two-component thermal model. This can be used for identification of lava flow emplacement style and the calculation of lava flow heat and volume flux. The multispectral infrared and visible imaging spectrometer (MIVIS) is an airborne sensor equipped with 72 bands in the short infrared range and 10 bands in the thermal infrared region of the spectrum. We used MIVIS acquired for Mount Etna (Italy) during the July–August 2001 eruption to solve the dual band equations in an unconstrained fashion using three bands of unsaturated data. Our results suggest a complex thermal structure for Etnean lava flows. This is characterized by a downflow transition from a lightly crusted active channel to a more heavily crusted distal section, both surrounded by zones of stagnant cooling flow where exposed molten material is absent and maximum temperatures are thus lower. The total flow field effusion rate obtained for 29 July 2001 (0700 local time) of 8–16 m3/s is in excellent agreement with that obtained from ground-based measurements and Advanced Very High Resolution Radiometer data. Flow-by-flow effusion rates obtained from the MIVIS data vary depending on whether the vent is linked to the central conduit or the dyke that was injected from greater depth, as well as vent elevation, with lower elevation vents experiencing higher effusion rates.