Recognition of periAdriatic Seismic Zones Most Prone to Next Major Earthquakes: Insights from a Deterministic Approach

The distribution of historical earthquakes indicates that a large portion of the Italian territory could be hit by strong earthquakes (e.g., Guidoboni et al. 2007). Since a large part of the building patrimony in Italy was realized without taking into account adequate antiseismic criteria (e.g., Di Pasquale et al. 2005; Crowley et al. 2009), it would be economically very difficult in the near future to achieve a significant mitigation of seismic risk in such a large zone. This objective could more easily be obtained if reliable information was available about the zones most proneto next strong earthquakes, where the limited resources now available could be concentrated. An attempt at obtaining such kind of information could be made by taking into account the possible connections between the spatio-temporal distribution of major shocks and the progressive development of tectonic processes in the central Mediterranean region, which are mainly related to the complex short-term kinematics of the Adriatic plate. It is known that each strong shock triggers a perturbation of the strain field that propagates in the surrounding zones (post-seismic relaxation, e.g., Pollitz et al. 2006; Ryder et al. 2007; Ergintav et al. 2009; Ozawa et al. 2011). When the effects of such perturbation reaches other seismic zones they may modify the probability of fault activation or even cause an earthquake when the fault involved is close to seismic failure. The possibility that this phenomenon induces seismicity has been pointed out in a number of papers (e.g., Anderson 1975; Rydelek and Sacks 1990; Pollitz et al. 1998, 2004, 2012; Mikumo et al. 2002; Freed 2005; Freed et al. 2007; Brodsky 2009; Lay et al. 2009; Durand et al. 2010; Luo and Liu 2010; Viti et al. 2012, 2013), which show that the time and place of occurrence of a number of major shocks are compatible with the expected effects of post-seismic relaxation induced by triggering events. In particular, this phenomenon has been recognized for some Italian zones (Southern Apennines and Calabria) whose seismic activity seems to be significantly influenced by major seismic crises in Hellenic and Dinaric zones respectively (Viti et al. 2003; Mantovani et al. 2008, 2010, 2012). The fact that past seismic activity may affect the spatio-temporal distribution of next shocks in the tectonic context here considered is instead supported by the time pattern of major earthquakes that occurred at the main periAdriatic zones since 1400 A.D. In the next section, we describe the evidence that may support the plausibility of the proposed approach and we discuss on how it may provide insights into the location of next strong earthquakes in the Italian peninsula.