III. FIRST RESULTS The area is seismically active [Chiodini et al., 2004; De Luca et al., 2009] and paleoseismic events have occurred in the Gran Sasso chain [Galli et al., 2002]. We decided to monitor the S13 borehole by continuously recording hydraulic pressure, temperature and electrical conductivity at a high sampling frequency using a 3-channel 24bit ADC, considering the characteristics of S13. The pressure sensor is connected directly to the borehole output, while the other two sensors are fed by groundwater drained into S13 borehole at 1 bar after a pressure reducing device. The hydraulic pressure of S13 borehole varies in the range of 24-28 bar during the year, consistent with a water table above of at least 250-300 m. During the 17 months of recording the water pressure signal followed the sun/moon tides very closely (Fig. 3).