Acknowledgements
This work was partially funded by the Italian National Research Council (PTA11011: Struttura crostale ed evoluzione geodinamica della penisola italiana - Partecipazione al Progetto CROP) and by the Italian Presidenza del Consiglio dei Ministri – Dipartimento della Protezione Civile (DPC) (DPC-INGV Seismological Projects). Scientific papers funded by DPC do not represent its official opinion and policies.