Alfia Pasquini (*), Tommaso Colonna (*), Matteo Burrini (**), Enrico Guastaldi (*) & Nicola Corrias (*)(*) Center of Geotechnologies, University of Siena. E-mail: pasquini9@unisi.it (**) Geotermitalia srl. E-mail: info@geotermitalia.it