Mapping fumarolic fields in volcanic areas: A methodological approach based on the case study of La Fossa cone, Vulcano island (Italy)

Abstract

Changes in the activity state of a volcano can be inferred by monitoring the steam flux from fumarolic fields, in terms of 4D (x, y, z, time) variations in temperature and extension of the zone. During the last decades, several studies in this field have been conducted worldwide, and at Vulcano island (Italy) in particular. Both direct and remotely sensed measurements have been used for identifying thermally anomalous areas, but the possible role of the hydrothermal alteration of volcanic products, producing a sealing effect that obscures the surface thermal evidence of fumarolic activity, have never been explored. The novelty of the present study, carried out at La Fossa cone (Vulcano Island), was the integration of direct and remotely sensed temperature measurements with the evaluation of soil permeability, for the precise mapping of areas where shallow hydrothermal circulation could occur even in the absence of surface evidence. The main results of this study concern the role of a coating found on rock surfaces and regolith in introducing mapping errors, especially during diachronic temperature surveys based on remotely sensed measurements.