Lithosphere Structure, Processes, and Physical State of the Alpine‐Apennine System

Abstract
Tomographic images of the lithosphere are the first step to constrain the evolution of mountain
belts and their interaction. By inverting new high-quality P- and S-wave arrivals that sample the entire
lithosphere, we determined Vp and Vp/Vs models with reliable resolution in the critical depth range (40–80 km)
where plates of the central Mediterranean area interact. This data set yields homogeneous representation of
the 3D structure over a critical area at a regional scale. Here, we show that the Alps derive from a laterally
continuous underthrusting of the European plate and that the Adria lithosphere was delaminated after the
collision. Tomograms resolve the lateral changes of the continental versus oceanic subduction along the Alpine
belt and identify original evidence of fluids beneath the orogens able to facilitate the current deformation.

Plain Language Summary
A high resolution imaging of the lithosphere/asthenosphere system
is crucial to understand tectonic processes of orogens and subductions. The Alpine chain is an exemplary
case of complexity, with its lateral heterogeneity and changes. The largest seismic array ever developed in
the Alpine chain (Alparray Seismic Network) has enabled the creation of a high-quality seismic data set
contributing to new images of the entire central Mediterranean area. The novelty of this work lies in the
enhanced resolution of velocity anomalies in a critical depth range (35–80 km) and with optimal homogeneity
at the regional scale. The new 3D Vp and Vp/Vs models allow us to get insights into many open questions about the structure and evolution of the circum-Mediterranean orogens.