Surface hydrothermal alteration mapping at Vulcano Island using MIVIS data

Abstract

Remotely sensed data (airborne hyperspectral Multispectral Infrared and Visible Imaging Spectroradiometer (MIVIS) data) were used to map active hydrothermal areas at Vulcano island (Sicily), related to a shallow magmatic chamber inducing hot fluid movements in the overlying rocks. A multispectral analysis was carried out using selected MIVIS band combinations and field spectra of selected altered surfaces. Results were checked by field survey, especially in the most active La Fossa crater area, where the zonation of a superficial high sulphidation hydrothermal system was reconstructed. The band selection used was able to clearly discriminate between fresh and hydrothermally altered rocks, especially at La Fossa crater; but differences between advanced argillic and the silicic alteration facies, as identified by field spectra, were not recognized, probably due to the occurrence of fumaroles. Despite the bias introduced by vegetation cover, illumination conditions and buildings, previously unrecognized sites of potential hydrothermal alteration and fumaroles were mapped in the northern sector of Vulcano island.