GNGTS 2016 - Atti del 35° Convegno Nazionale

408 GNGTS 2016 S essione 2.2 Multidisciplinary approach to the study of environmental effects related to low to moderate magnitude earthquakes: the case study of the December 2013 – February 2014 Matese seismic sequence E. Valente 1 , A. Ascione 2 , M. Cozzolino 1 , S. Porfido 3 1 Dipartimento di Scienze Umanistiche, Sociali e della Formazione, Università degli Studi del Molise, Campobasso, Italy 2 Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Università degli Studi Federico II, Napoli, Italy 3 Istituto per l’Ambiente Marino e Costiero, IAMC-CNR, Napoli, Italy Introduction. Seismically induced environmental effects are typical of moderate to high magnitude seismic sequences. These phenomena have been widely observed worldwide and they characterise also the seismic history of the SouthernApennines fold and thrust belt (Porfido et al. , 2002). In the last years an increasing interest has been devoted to the study of seismically induced environmental effects as their recognition is a valuable method to intensity assessment for strong earthquakes, to compare earthquake intensity assessment worldwide and to compare effects of recent, historical and pre-historical earthquakes (Serva et al. , 2015). Based on these consideration, a new intensity assessment scale, the ESI scale, has been developed, which allows the estimation of earthquake intensity only based on seismically induced ground effects and not on damages to man-made structures (Michetti et al. , 2007). We have carried out a study on active tectonics in the southern Matese area (Southern Apennines) based on Quaternary geology, geomorphology, geophysics, seismology, and addressed to the recognition of environmental earthquake effects induced by the Mw = 5.0, 29 th December 2013 Matese earthquake. The Matese massif is a ~2000 m high ridge located in the Campania-Molise sector of the southern Apennines. The southern Apennines is a NE-directed fold and thrust belt formed in Miocene to Quaternary times, with thrusting coexisting with back-arc extension in the southern Tyrrhenian basin since the late Miocene (Cinque et al. , 1993). In the study area, tectonic units consist, from the top, of carbonate successions (Apennine Platform, outcropping in the Matese ridge), pelagic basin successions (Molise-Sannio Basin, outcropping to the N and E of the ridge), and the buried Apulian platform carbonates. The thrust pile is dissected by NW-SE extensional structures and E-W trending high-angle faults generally showing left-lateral activity overprinted by either dip-slip or oblique right-lateral motion associated with reactivation during the Middle Pleistocene to Present tectonic regime (Mazzoli et al. , 2000, and references therein). The area including the southern Matese ridge and adjoining valleys is affected by several extensional faults showing geomorphological-stratigraphical evidences of activity during the late Quaternary. These include a dense net of minor (few km long) faults, mostly with NW-SE, E-W and N-S trends, and some major (tens of km long) extensional fault zones with overall WNW-ESE trends (Cinque et al. , 2000; Valente et al. ., 2015a). TheDecember2013–February2014Matese seismic sequenceandrelatedenvironmental effects. From the 29th December 2013 to the end of February 2014 the Matese area has been struck by a low to moderate magnitude seismic sequence. The sequence started on the 29 th December 2013 at 17:03:25 UTC with a ML = 2.7 event that was followed by the strongest event of the entire sequence, with Mw = 5.0 at 17:08:43 UTC. The sequence continued with hundreds of low magnitude earthquakes (Ml ~ 2-3) until the 20 th January 2014 when a second large shock occurred (Mw = 4.2 at 07:12:40 UTC). Lower magnitude earthquakes continued to struck the Matese area until the end of February 2014, when the seismic sequence ceased (http://iside.rm.ingv.it/ ). The Mw = 5.0 main shock was characterised by a normal faulting focal mechanism and a NE oriented T axis (http://cnt.rm.ingv.it/event/2874261) , consistent with moment tensor solutions for 31 small to moderate events of the entire December 2013- January 2014 seismic sequence (D’Amico et al. , 2014). The location of the epicentre and the hypocentre depth of the main event are still debated. Epicentre locations are clustered south of