Crustal and deep seismicity in Italy: A review

In this paper I review the main features of the seismic activity of Italy, summarizing historical and recent seismological data available for our region. I concentrate mostly on the recent instrumental data that have been collected by permanent and temporary networks in the past 20 years. I first describe the deep structure of the lithosphere-asthenosphere in Italy, as inferred by seismic tomography, and its relationship with deep and shallow seismicity. Then, I summarize the main characteristics of the shallow seismicity recorded in the past decades. These data, i. e. tens of thousands earthquakes over a broad magnitude range, have brought relevant new information on the type and amount of seismic deformation that is released day by day through earthquakes. Over the past years, our ability to determine the geometry and kinematics of seismogenic faults has increased dramatically, thanks to modern instruments and new techniques of analysis. I show some examples of what seismologists have learned by the use of regional networks and of dense temporary arrays, in three of the most active regions of Italy that are characterized by different type of seismicity: the Umbria-Marche Apennines, affected by normal faulting earthquakes, the outer front of the northern Apennines, characterized by compressive earthquakes, and the southern Apennines foredeep, where strike-slip earthquakes occur.