GNGTS 2022 - Atti del 40° Convegno Nazionale

GNGTS 2022 Sessione 1.1 67 • B-value fit: it allows to correct the fit of the line that passes through the cumulative curve. Figure 1 summarizes some aspects of all the Italian seismicity from 1985 to 2022. In the distribution of magnitude values vs time (fig. 1a) it is possible to notice the densities of distribution of black dots higher in some precise years, these representing important seismic swarms and earthquakes. Fig. 1 b represents the variation of the b -value in relation to time. We note that there are important variations and above all the achievement of important values ​in specific moments and years. The maximum curvature estimated for the whole INGV catalogue, period 1985-2022 is showed in fig 1 c. The completeness magnitude was found to be 2.7, with a correction factor of 1.5. The b-value is 1.1 +/- 0.01 and a-value is 7.434. Analogously, fig. 1 d represents the maximum curvature estimated only for the period from 1985 to 2005, before the upgrade of the Italian Seismic Network. For these data the completeness magnitude is 2.8 with a correction factor of 0.4. The b-value is 1.21 +/- 0.01 and the a-value is 7.484. Finally, fig.1 e represents the maximum curvature estimated only for the period from 2005 to 2022. In this case the completeness magnitude is 2.0 with a correction factor of 0.8. The b-value is 0.97 +/- 0.00 and a-value is 6.658. Fig. 1 - Some graphics about seismic catalogue of INGV. a)Time series 1985-2022 b)b-value variation relative time c) curve cumulative for 1985-2022 d)curve cumulative for 1985-2005 e)curve cumulative for 2005-2022. Among the various possibilities of ZMAP, there is that of calculating the spatial variation of the fundamental parameters of the Gutenberg-Richter formula. In fact, it was decided to create various maps to estimate the magnitude of completeness, b-value and the standard deviation of b. For the creation of these maps, attention has fallen on recent seismicity, i.e. from 2015 onwards, including the seismic crisis in central Italy (2016-2018) and also the central southern crisis, including the 2017 Ischia earthquake and other events. Also in this case ZMAP gives the possibility to change the input parameters.