Structure and properties of the Ivrea body and of the Alps-Apennines system as revealed by local earthquake tomography

Abstract

The diverse studies carried out with geophysical and geodetic data in the last decades greatly improved the knowledge of the Alps-Apennines system. However, most of these studies were limited to portions of the system or to the shallow structures, and for these reasons reconstruction of the tectonic setting for a larger area and for the deeper layers is still open to different approaches and interpretations; in particular, very little is known about the deeper conjunction between the two chains. In the recent past, many studies have made use of tomographic techniques to investigate the area under study. This paper is the natural extension and completion of the previously published works. Its aim is to propose a more detailed Vp and newer Vp/Vs tomographic images of the Alps-Apennines system and of the Ivrea body by profiting from the increased availability of good S phase pickings and by making use of improved inversion techniques. Some of the main tools developed in the tomographic techniques to evaluate the reliability of the obtained tomo images are used to outline the actual resolution power of the method-data coupling. The inversion results suggest that the Ivrea body may be characterized by a significant anomaly in the Vp/Vs ratio. The conjunction between Alps and Apennines remains partly unresolved due to the complexity of the interacting plates at greater depth.