| Abstract: | The measured underground temperatures of four boreholes (Rapagnano, Giulianova, Imola and San Marino) drilled into clayey formations in the central regions of Italy, as part of a geothermal research program, have shown that they are affected by more or less regular disturbances. The absence of groundwater movements in these formations, the relative flatness of the topography around the holes and the shape of the disturbances have led them to be considered as the effects of some recent local climatic variations.An inverse theory approach has been used to construct the local surface thermal history. It was not possible to compare it with the temperatures observed by meteorological instruments over the areas close to the boreholes because these data are not available. The results have been compared successfully with the climatic variations over the Northern Hemisphere during the last century. Among several models of the surface forcing temperature, the most reliable one for Rapagnano is represented by a sinusoidal wave, while a parabolic decrease holds good for Giulianova.Suggestions are given for geothermal prospecting. |
