GNGTS 2015 - Atti del 34° Convegno Nazionale

22 GNGTS 2015 S essione 1.1 Fig. 3 – Detection (left side) and location (right side) threshold, as magnitude M L unit. Observed ambient noise levels are used for FIU, POV1 and POV4 stations, while for POV2 and POV3, modified ambient noise are simulated (the same seismic noise recorded at POV1 site). For the SPCA station a theoretical level of noise from borehole station at 200 m in depth, is also taken into account. From top to bottom, the above- mentioned distributions, in the extended domain, are shown at 1.0, 2.5, 4.0 , 6.5 and 9.0 km in depth. The detection threshold is evaluated by imposing that the seismic event was recorded by at least 3 stations of the network.