Surface temperature monitoring by Earth Observation optical data, drones and field campaigns in the Central Italy geothermal districts

The sites of high-temperature geothermal energy resources are commonly marked by thermal manifestation area where fumaroles, steaming grounds, hydrothermally altered grounds, hot springs, volcanic gas vents, and mud pools occur. These areas must be commonly subjected to geophysical monitoring where the measurements of shallow and surface temperatures may play an important role. Surface thermal signatures may also be used to define the evolution of development of shallow structures present on both volcanic districts and geothermal areas and possibly related to tectonic activity along active faults.

The Tyrrhenian margin of the Italian peninsula is characterized by several high and medium enthalpy geothermal systems and in Tuscany several geothermal systems with a large-scale steam-dominated geothermal anomaly are presents. The different geological assets and thermal behavior of these areas correspond to surface thermal anomalies that may be very different both for the maximum temperatures and for the size and distribution on the ground. In this context, systematic global cataloging of thermal anomalies as measured from high spatial resolution spaceborne sensors and acquired with thermal camera installed on drones are still in their infancy. Our goal is to create and analyze a catalog of data by examining the magnitude, frequency and distribution of Tuscany geothermal districts thermal signatures at the highest available spatial resolution ranging from the hundreds of meters per pixel of satellite thermal images to the tenths/hundreds of centimeters per pixel of the thermal images taken by the drones. Remote sensing and drones represent an effective and expedite tool to acquire infrared images when there are large extents of areas affected by thermal anomalies. The maps obtained by EO data acquiring thermal imagery at suitable spatial resolution and drone measurements are orthorectified and geocoded in order to be superimposed on digital terrain models or on the orthophotogrammetric mosaic obtained after processing photos acquired by drone. This allows, for example, to follow the evolution of thermal anomalies, that may represent a modification of the current state of the geothermal field and a possible hazard for both the population and for industrial assets.