The measurements of 4D temperature distribution in Earth Science by distributed optical fiber sensors: an experimental approach to monitoring temperature and heat transfer dynamics at the Campi Flegrei volcano (Italy)

We present the first results of long- term monitoring of temperature-depth profiles at the active volcanic area of Campi Flegrei caldera, Italy. The measurements were carried out along a 76 meters-deep borehole already equipped with a borehole strain-meter. We installed a cable containing a loop of optical fiber in order to use a fiber-optics distributed temperature sensor based on stimulated Brillouin scattering. The obtained data are consistent with results of both deep and surface geothermal explorations available in the literature and indicate that the geothermal gradient can be efficiently measured and monitored by the proposed technique.