GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Applicaton to real case: the Mw 4.6 Central Italy earthquake The method was then applied to study the Mw 4.6 event of March 2023 in central Italy, using data from the Italian seismic network (RSN (Amato et al., 2008) and the Italian accelerometry network (RAN (Costa et al., 2022)). We compute the ASTFs through the EGF deconvoluton using the P and S waves. We calculated the second seismic moment to obtain informaton about the directvity and source parameters. The main parameters calculated with this method are the following = 1.16 km, = 0.615, = 0.14 s, = 1.86 m/s, dir = 64, stress drop = 7.37 MPa). The relatvely small value of is possibly due to the poor resoluton of the vertcal component and can be explained by the interacton of two factors: the vertcal rupture plane and the small number of statons in the immediate vicinity of the epicenter (< 5 km). Conclusions The use of second-moment tensors to determine the source parameters, including directvity, of moderate-magnitude earthquakes could be a valuable tool to improve our understanding of the source dynamics in a given area and to the risk mitgaton. One possible applicaton of the second- moments method to small earthquakes would be to identfy portons of large faults that produce super-shear ruptures and correlate them with the geology of the fault zone. The second moments method also provides lower constraints on rupture velocity, which can be partcularly useful for unilateral ruptures. However, before the results can be interpreted, the resoluton limits of the method need to be known due to the possible uncertaintes of the parameters used as inputs to the computatonal procedure. To overcome the difcultes related to the analysis of noisy signals in the tme domain, which can be an important limitaton in the calculaton of ASTFs and consequently the source duraton for low magnitude events, an experimental approach based on the frequency domain is currently being developed. Although the frequency domain deconvoluton-based method is currently more tme consuming than tme domain deconvoluton, it can be used in situatons where the determinaton of reliable ASTFs is difcult due to noise, which is ofen the case for low magnitude earthquakes. Acknowledgements We are deeply grateful to the Italian Department of Civil Protecton – Presidency of the Council of Ministers for funding this research.