GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 2.1 GNGTS 2024 measured period is reported in Fig. 3 bottom, it appeared to grow persistently for about half an hour before this minor event, which corresponded to a gravity decrease. Fig. 3 – A gravity recording of the two hours between the seismic event occurred in Ceneselli on July 17, 2011. The seismogram recorded at the same position of the damped pendulum is reported on the top, where the blue area highlights the seismogram length while the red areas highlight direct and reverse gravimeter responses. Another gravity recording of the two hours between the seismic event occurred in Ceneselli on October 28, 2023, on the bottom. The gravity measurements are indicated by a broken line where the thick line indicates its average trend. Red areas evidence a trend of an increasing period that anticipated the shock, then the period suddenly decreased