Issue 51

F. Clementi et alii, Frattura ed Integrità Strutturale, 51 (2020) 313-335; DOI: 10.3221/IGF-ESIS.51.24 324 in sequence with a set of null velocities for a 1 second at the beginning, before the first event used, and, in the same way, with other equal sets of null velocities among the other registrations implemented. The location of the epicentres of the four main shocks and of the civic tower of Amatrice are plotted in Fig. 1 , and the comparison between the characteristics of the seismic accelerations is reported in Tab. 2 , where [28–30]:  R jb , is the Joyner-Boore distance, known as the smallest spacing from the site to the surface projection of the rupture surface;  R rup , is the shortest distance between the site and the rupture surface;  R epi , is the distance estimated by the geometric swap. Seismic event M L Depth (km) Station Class EC8 R jb [km] R rup [km] R epi [km] Channel NS PGA (cm/s 2 ) Channel EW PGA (cm/s 2 ) Channel UD PGA (cm/s 2 ) 24/08/2016 6.0 8.1 AMT B* 1.38 4.62 8.50 368.39 -850.80 391.37 24/08/2016 5.4 8.0 AMT B* - - 20.90 -93.28 105.58 63.77 26/10/2016 5.9 7.5 AMT B* 25.93 26.09 33.30 -58.55 90.74 -49.11 30/10/2016 6.1 9.2 AMT B* 10.12 11.49 26.40 393.63 521.62 317.82 Table 2 : Characteristics of main earthquakes recorded in Amatrice (AMT) station during the main shocks of the Central Italy seismic sequence of 2016, where * indicates that site classification is not based on a direct Vs,30 measurement Figure 12 : Numerical cumulative damages of the civic clock tower of Amatrice (Rieti, Italy) under the four main shocks recorded in the village during the Central Italy seismic sequence of 2016 for both configurations, with and without the steel chains, and with the friction coefficient equal to 0.30 in the bell cell and 0.50 in the other parts.