GNGTS 2019 - Atti del 38° Convegno Nazionale

106 GNGTS 2019 S essione 1.1 TEST OF SOURCE-PARAMETRES INVERSION OF THE 11 JANUARY 1693 CATANIA EARTHQUAKE IN A NEW CONTEST F. Pettenati, D. Sandron Istituto Nazionale di Oceanografia e di Geofisica Sperimentale OGS, Trieste, Italy Introduction. The preliminary results of the 11 January 1693 Catania earthquake, after the the new inversions of macroseismic intensity data, using the KF technique, are shown. The inversions are constrained on four source hypotheses, formulated by other studies, including those related to the inversions of some of the four sources indicated. The choice of constrained inversions is also due to the large extension of the area investigated (between teh hinterland of south-eastern Sicily and the Ionian Sea). Four source hypotheses have been taken, including a new one, compared to those already investigated. At first, a macroseismic dataset from the CFTI (Boschi et al. , 1997) catalog was selected within a squared area with a side of 200 km, and centre the macroseismic epicentre. Subsequently a reduced dataset was used, keeping only the data of the January 11 event outside the zone of damage (intensity greater than V) of the previous shock of January 9 in the same area. The results always confirm the ground hypothesis compatible with the Scicli-Ragusa-Monte Lauro structure. Modelling. The Mw 7.3 (CPTI15) earthquake in south-eastern Sicily of 11 January 1693, historically has been associated to the large offshore structure Ibleo Maltese. Sirovich and Pettenati (1999, 2001), led to the formulation of a hypothesis in the Catania hinterland, denying the source at sea. The method used is the macroseismic data inversion of the KF kinematic function (Pettenati and Sirovich, 2007), driven by genetic algorithms. The question of the great tsunami, that accompanied the earthquake, remains and this makes the ground source hypothesis falsifiable. We must also bear in mind the event of January 9th, an earthquake of Mw 6.5 occurred 40 hours before. Although the macroseismic catalogs distinguish the two earthquakes, for the hazard estimates, it is possible that the effects of this shock have in part influenced the damage estimates of the following event. Furthermore, we need consider five sites along the coast (Brucoli, Augusta, Belvedere, Siracusa and ancient Avola, Fig. 1), with an intensity decidedly lower than the XI estimates immediately placed in the hinterland. Starting from the work of 2001 (Sirovich and Pettenati, 2001), to have a comparison, we started from the CFTI database (Boschi et al. , 1997), taking the data inside a window of side of 200 km, with centre the macroseismic epicentre. The three hypotheses considered in the 2001 work, were then tested: Scarpata Ibleo Maltese (IBLMAL); the Graben Scordia Lentini (SCOLEN) and the Scicli-Ragusa-Monte Lauro structure (SCICLI) (Fig. 1). A new hypothesis at sea was tested, identified in a portion to the north of the tear fault recognized in the western Jonio (Del Ben et al. , 2008), also Fig. 1 - Area of the study. In legend the name of the five sites interested of a fall of intensities respect the hinterland. The two intensities reported in the brackets are refferd to 9 – 11 January event.