GNGTS 2013 - Atti del 32° Convegno Nazionale

Kerrich, R., 1986. Fluid infiltration into fault zones: chemical, isotopic and mechanical effects. Pure Appl. Geophys., 124, 225-268. Macchiavelli, C., Mazzoli, S., Megna, A., Saggese, F., Santini, S., Vitale, S.; 2012: Applying the Multiple Inverse Method to the analysis of earthquake focal mechanism data: new insights into the active stress field of Italy and surrounding regions. Tectonophysics, 580, 124-149. Milia, A., Torrente, M.M.; 1999: Tectonics and stratigraphic architecture of a peri-Tyrrhenian half-graben (Bay of Naples, Italy). Tectonophysics, 315, 301-318. Minissale, A.; 2004: Origin, transport and discharge of CO2 in central Italy. Earth Sci. Rev., 66, 89-141. Patacca, E., Scandone, P.; 2001: Late thrust propagation and sedimentary response in the thrust belt-foredeep system of the Southern Apennines (Pliocene-Pleistocene). In: Vai, G.B., Martini, I.P. (Eds.), Anatomy of a Mountain: the Apennines and Adjacent Mediterranean Basins. Chapman and Hall, London, p. 401-440. Rolandi, G., Bellucci, F., Heizler, M.T., Belkin, H.E., De Vivo, B.; 2003: Tectonic controls on the genesis of ignimbrites from the Campanian Volcanic Zone, southern Italy. Mineral. Petrol., 79, 3-31. Santangelo, N., Ciampo, G., Di Donato, V., Esposito, P., Petrosino, P., Romano, P., Russo Ermolli, E., Santo, A., Toscano, F., Villa, I.; 2010: Late Quaternary buried lagoons in the northern Campania plain (southern Italy): evolution of a coastal system under the influence of volcano-tectonics and eustatism. It. J. Geosci., 129/1, 156-175. Santo, A., Ascione, A., Del Prete, S., Di Crescenzo, G., Santangelo, N.; 2011: Collapse sinkholes distribution in the carbonate massifs of central and southern Apennines. Acta Carsologica, 40/1, 95-112. Sartori, R.; 1990: The main results of ODP Leg 107 in the frame of Neogene to Recent geology of the PeriTyrrhenian areas, in Kastens, A., Mascle, K.J., et al ., eds., Proceedings of ODP, Scientific Results, 107, College Station, TX (Ocean Drilling Program), 715-730. Sartori, R.; 2003: The Thyrrhenian backarc basin and subduction of the Ionian lithosphere: Episodes, 26, 217-221. Sibson, R.H., 2000. Fluid involvement in normal faulting. Geodynamics, 29, 469-499. Toutain, J.P., Baubron, J.C.; 1999: Gas geochemistry and seismotectonics: a review. Tectonophysics, 304, 1-27. An in-depth analysis of seismic episodes: the example of the 2010 Sampeyre swarm and the 2013 Lunigiana sequence S. Barani, R. De Ferrari, G. Ferretti, M. Pasta, D. Scafidi, D. Spallarossa, C. Turino DISTAV, Università degli Studi di Genova, Italy Foreword and scope of work. The analysis of earthquake sequences and swarms provides useful hints to identify and characterize the seismogenic structures of an area, to investigate earthquake source properties, to study the propagation of seismic waves, and to investigate the recurrence of earthquakes. Accurate location methods, such as those based on the “master event” (e.g., Peppin et al. , 1989; Joswig and Schulte-Theis, 1993; Cattaneo et al. , 1999) or “double difference” (e.g., Waldhauser and Ellsworth, 2000; Zhixian et al. , 2003; Yang et al. , 2005) techniques, and seismogram cross-correlation are usual tools in these fields of research. For instance, seismogram cross-correlation has often been applied to identify distinct lineaments belonging to a fault system and to define clusters of dependent events (e.g., Shearer, 1998; Astiz et al. , 2000). Similarly, the double-difference technique has been widely used to study fault structures and to investigate the spatial and temporal evolution of seismic sequences or swarms (e.g., Prejean et al. , 2002; Schaff et al. , 2002; Waldhauser and Ellsworth, 2002; Fukuyama et al. , 2003). Note that these methods have been generally applied to analyze low-to-moderate magnitude seismicity episodes, including micro-seismicity events and aftershocks. Indeed, location of small earthquakes is one of the primary tools used by seismologists in order to constrain fault locations and orientations and to study the seismogenic process. In this paper, we apply a comprehensive approach, including major techniques used to analyze sequences and swarm (i.e., waveform cross-correlation, double-difference location, and micro-event detection), to exhaustively investigate the Sampeyre swarm (left panel of Fig. 1), which occurred between October and November 2010 in the Southwestern Alps, and the recent Lunigiana sequence which started on June 21, 2013 in the Northern Apennines (Fig. 2). Regarding the Sampeyre swarm, 550 earthquakes (the strongest one had a magnitude of 3.2) were recorded and localized by the Regional Seismic network of Northwestern Italy – RSNI 17 GNGTS 2013 S essione 1.1