GNGTS 2022 - Atti del 40° Convegno Nazionale

242 GNGTS 2022 Sessione 2.1 in Fig. 2 (c) and (d). The relative amplification varies by a factor of around 10. We determine the seismic moment and the corner frequency by fitting an ω 2 -model to the obtained source spectrum. Fig. 2 - Regional attenuation models against hypocentral distance for frequencies from 0.3 to 25 Hz for (a) region A and (b) region B. (c) Site amplifications obtained by the spectral decomposition relevant to the reference site, CH.LLS (red curve). (d) Source spectra retrieved through the spectral decomposition approach. We determine the seismic moment and the corner frequency by fitting the corrected source spectra with an ω 2 -model. Finally, we evaluate the resulting stress drops for different source origins (induced and tectonic earthquakes) under the same assumptions (Fig. 3). Resulting stress drops show a clear scaling relationship with moment magnitudes, with stress drop increasing with earthquake magnitude for the tectonic events. The distributions of stress drop for two source origins are in the different ranges, which are in the range of 0.01-1 MPa for induced events and 0.1-100 MPa for the tectonic events. The scaling relationships of stress drops for two source origins confirm that the stress drop of the induced events are not following a scale with earthquake magnitude. Acknowledgement. This study was supported by the European Union’s H2020-MSCA-ITN-2018 program under grant agreement No 813137, project URBASIS.