GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.1 125 Kijko A., Singh M.; 2011: Statistical tools for maximum possible earthquake magnitude estimation . Acta Geophysica, 59 , 674-700, DOI 10.2478/s11600-011-0012-6. Koulali A., Ouazar D., Tahayt A., King R.W., Vernant P., Reilinger R. E., McClusky S., Mourabit T., Davila J. M., Amraoui N.; 2011: New GPS constrains on active deformation along the Africa-Iberia plate boundary . Earth Planet. Sci. Lett. 308(1), 211-217, DOI 10.1016/j.epsl.2011.05.048. Palano M.; 2015: On the present-day crustal stress, strain-rate fields and mantle anisotropy pattern of Italy . Geophys. J. Int., 200 (2), 969-985, DOI 10.1093/gji/ggu451. Savage J. C., Simpson R. W.; 1997: Surface strain accumulation and the seismic moment tensor . Bull. Seismol. Soc. Am., 87 , 1345-1353. Shen Z.-K., Wang M., Zeng Y., Wang F.; 2015: Optimal interpolation of spatially discretized geodetic data . Bull. Seismol. Soc. Am., 105 , 2117-2127, DOI 10.1785/0120140247. Wells D. L., Coppersmith K. J.; 1994: New empirical relationship among magnitude, rupture length, rupture width, rupture area, and surface displacement . Bull. Seismol. Soc. Am., 84 , 974-1002. THE CAMPOTOSTO LINKAGE FAULT ZONE IN BETWEEN THE 2009 AND 2016–2017 SEISMIC SEQUENCES OF CENTRAL ITALY: IMPLICATIONS FOR SEISMIC HAZARD ANALYSIS E. Tondi 1 , D. Jablonská 1 , T. Volatili 1 , M. Zambrano 1 , M. Michele 2 , S. Mazzoli 3 , P.P. Pierantoni 1 1 School of Science and Technology - Geology Division, University of Camerino, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy 3 Department of Earth, Environmental and Resources Sciences- University of Napoli Federico II, Italy The Central Italy has been struck by severe earthquakes along the Apennine chain, as documented in the historical sources (Rovida et al. , Eds., 2015). The most significant earthquakes, clustered along the Central Apennines Fault System (CAFS in Cello et al. , 1997), have been documented in 3 periods over the last millennium: in the 13 th -14 th and 17 th - 18 th centuries; and the recent events from the 1970s till present (Tondi and Cello, 2003). The last decades witnessed several devastating earthquakes resulting in hundreds of casualties (i.e. 1997 Colfiorito-Sellano Mw=6.0; 2009 L’Aquila Mw=6.3 and 2016 Amatrice-Visso-Norcia Mw max=6.5). These events were caused by the reactivation of NW-SE striking normal faults dipping SW (Fig. 1; Tondi et al. , Eds., 2009, Pantosti and Boncio, Eds. 2012, Civico et al. , 2018; Villani et al. , 2019). The Fig. 1 shows the seismogenic faults related to the mainshocks of the 1997 Umbria- Marche, 2009 L’Aquila and the 2016 Amatrice-Visso-Norcia seismic sequences. The three south-west dipping seismogenic faults have been modelled on the base of the available focal mechanisms and the seismic moment detected during the following mainshocks: 1. CSF - 26 th September 1997 Umbria-Marche earthquake (Mw=6.0); 2. PF - 6 th April 2009 L’Aquila earthquake (Mw=6.3); 3. MVF - Cumulative of 24 th August 2016Amatrice earthquake (Mw=6.0), 26 th October 2016 Visso earthquake (Mw=5.9), 30 th October 2016 Norcia earthquake (Mw=6.5). The Campotosto area represents a step in between the PF and MVF. This area has been affected by seismic swarms with magnitude ranging from 5.0 to 5.5 during both the 2009 and the 2017 seismic sequences, as shown in Fig. 1 (Valoroso et al. , 2013; Chiaraluce et al. , 2017). The hypocentre clusters of the 2009 and 2017 seismic sequences in the Campotosto area occurred at a depth of more than 5km, which suggests the presence of a deep structure, that can be interpreted as a relay-growing fault zone in between the seismogenic PGF and MVF. According to this interpretation, the seismogenic potential of the relay zone, on the base of its dimension, is in the order of Mw=6.0 (even if all the faults belonging to the relay zone activate simultaneously). Moreover, for the same reason, the Campotosto area does not represent a seismic gap, as suggested by Falcucci et al. (2018).