GNGTS 2013 - Atti del 32° Convegno Nazionale

InSAR-measured crustal deformation transients associated to the Emilia and Pollino seismic sequences, 2011-2012 C.O. Tolomei, S. Salvi, G. Pezzo Centro Nazionale Terremoti - INGV, Roma, Italy Introduction. The occurrence and significance of crustal deformation transients in the seismic cycle is still a debated issue. The presence of mid- or short-term transient crustal deformation signals, has been fragmentarily reported for over a century, with different levels of quality and reliability (Roeloffs, 2006). Most of the reports deal with anomalies in the assumed steady inter-seismic deformation rates, often occurring in the temporal and spatial vicinity of large earthquakes (Rikitake, 1976; Wyss, 1991). More recently, observations have also focused on the observation of transients occurring during the post-seismic phase, when the stress changes imparted by the earthquake are relaxed, stimulating significantly faster crustal and lithospheric deformation than during the inter- seismic phase (Wright et al. , 2013). Thanks to the improved quality of GPS and InSAR data and analysis methods, new observations of long-term and short-term deformation transients are increasingly reported (Salvi et al. , 2012; Calais et al. , 2008; Furuya and Satyabala, 2008; Pritchard and Simons, 2006; Cakir et al. , 2005; Bernard et al. , 2004; Larson et al. , 2004; Dragert et al. , 2004; Miyazaki et al. , 2003; Ozawa et al. , 2002; Peltzer et al. , 2001). Some of these events are associated with post-seismic deformation, while others occur during the inter-seismic phase. Their duration ranges from weeks to years, with detected movements from mm/yr to cm/yr; their intensity can be large: the geodetic moment magnitude can exceed Mw=7 in subduction zones. Modeling and theoretical developments (Peng and Gomberg, 2010; Liu and Rice, 2007) suggest that most of these events can be generated by aseismic slip or slow-slip events, often located in the deeper parts of a larger fault which later release seismic slip (Miyazaki et al. , 2011; Roeloffs, 2006). This work, carried out within the 2012-2013 S3 INGV-DPC project Measurement and analysis of crustal deformation transients during the Emilia and Pollino seismic sequences, was aimed at the investigation of deformation transients using SAR Interferometry techniques in two test cases: the Emilia 2012, and the Pollino 2011-2012 seismic sequences. While Continuous GPS data are certainly the best suited for the detection of such transients (especially Fig. 1 – Envisat descending and ascending mean ground velocity map retrieved from SBAS approach. 202 GNGTS 2013 S essione 1.2