GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Results Two distnct periods of the temporal evoluton of seismicity appear evident in the curves of Fig. 2: the period between preceding events E1 and E2 and the one following these events, since the beginning of 2017 characterized by marked fuctuatons of all the parameters, and in partcular b- values and fractal dimension (Fig. 2b, c). The temporal variaton of the b-value can be related to crustal stress changes in a medium characterized by diferent mechanical propertes. The fractal dimension tme evoluton indicates a prevailing clustering of the earthquakes with a tendency to propagate linearly. The temporal variatons of the Shannon entropy (Fig. 2a) and η (Fig.2 d) quantfy the evolving organizaton and correlaton of seismicity within an area. Fig. 3 - a) distributon of the epicentres of the events with M C = 1 of the catalogue, in the region 10 km wide, centred on the secton A-B of Fig. 1, in three spatal windows of about 10 km in longitude and 6.7 km in lattude. The circles are the epicentres of the earthquakes analyzed with PCA: blue circles: zone 1; red circles: zone 2; green circles: zone 3. b) PCA solutons obtained by sliding a 30 events window along the events in zone 1; c) PCA solutons obtained by sliding a 30 events window along the events in zone 2; d) PCA solutons obtained by sliding a 30 events window along the events in zone 3. Yellow square: Maximum spatal axis; green triangle: intermediate spatal axis; blue diamond: minimum space axis; red dot: tme axis projecton on the space volume: if hollow, the verse is upwards. Black lines: planes normal to the spatal minor axes (blue diamond). (from Bressan et al., 2021, modifed).