GNGTS 2022 - Atti del 40° Convegno Nazionale

GNGTS 2022 Sessione 2.1 237 ABOUT THE ROLE OF NW-TRENDING FAULT SYSTEMS IN THE MESSINA STRAITS AREA G. Neri 1 , P. Pino 1 , D. Presti 1 , S. Scolaro 1 , S. D’Amico 2 , C. Navarra 1 , B. Orecchio 1 , A. Torre 1 1 Department of Mathematics, Computer Sciences, Physics, and Earth Sciences, University of Messina, Messina, Italy 2 Department of Geosciences, University of Malta, Msida, Malta Re-examining the HVSR data published in a previous paper (Scolaro et al. , 2018) we focus on a clear change of peak frequency occurring across a NW-SE segment located in the historical centre of the town of Messina. This change can reasonably be imputed to lateral heterogeneity of the sedimentary cover passing from southwest to northeast across the segment and, possibly, to an increase of the thickness of the sediment pile corresponding to a decrease of the HVSR peak frequency. These data may suggest the existence of a fault in correspondence of the segment. Neri et al. (2021) have shown that seismicity in the overall Straits area is often characterized by transtensional focal mechanisms with a right-lateral component. The same authors proposed a possible geodynamic interpretation of seismological evidences, according to which (i) southeastward rollback of the residual Ionian subducting slab, although very slow at present day, is a main source of extension in the Messina Straits area and (ii) southward decrease of trench retreat velocity when approaching the southern edge of the subducting slab produces a right-lateral component of faulting on NW-SE trending faults. Also, we remark here that one of the strongest earthquakes occurred in the Messina Straits after the 1908 one, the magnitude 4.9 earthquake of January 1975 offshore Reggio Calabria, was characterized by a dextral strike-slip mechanism, with several features similar to mechanisms of recent seismicity obtained by Neri et al. (2021). In the present work, we discuss a series of new analyses based on application of different geophysical and geological methodologies, with the aim of evaluating the real role of NW- trending fault systems in the Messina Straits, from the geodynamic point of view and with particular reference to seismogenesis in this high seismic risk area. References Neri G., Orecchio B., Presti D., Scolaro S., and Totaro, C.; 2021: Recent Seismicity in the Area of the Major, 1908 Messina Straits Earthquake, South Italy . Frontiers in Earth Science, 9 , 566, doi: 10.3389/feart.2021.667501. Scolaro S., Pino P., D’Amico S., Orecchio B., Presti D., Torre A., Totaro C., Farrugia D. and Neri G.; 2018: Ambient noise measurements for preliminary microzoning studies in the city of Messina, Sicily . Annals of Geophysics, 61 (2), doi: 10.441/ag-7711.