Deep Structure of Northern Apennines Subduction Orogen (Italy) as Revealed by a Joint Interpretation of Passive and Active Seismic Data

The Apennines is a well‐studied orogeny formed by the accretion of continental slivers during the subduction of the Adriatic plate, but its deep structure is still a topic of controversy. Here we illuminated the deep structure of the Northern Apennines belt by combining results from the analysis of active seismic (CROP03) and receiver function data. The result from combining these two approaches provides a new robust view of the structure of the deep crust/upper mantle, from the back‐arc region to the Adriatic subduction zone. Our analysis confirms the shallow Moho depth beneath the back‐arc region and defines the top of the downgoing plate, showing that the two plates separate at depth about 40 km closer to the trench than reported in previous reconstructions. This spatial relationship has profound implications for the geometry of the shallow subduction zone and of the mantle wedge, by the amount of crustal material consumed at trench. Depicting the structure of the Earth is a goal for all Earth scientists. Knowledge of the Earth's properties is fundamental for a number of societal challenges, from locating georesources to the mitigation of seismic risk. We investigate the structure of the Earth's crust beneath a well‐studied subduction orogeny, the Apennines (Italy), analyzing together different seismic data sets. The Apennines mountain chain were the locus of a number of middle‐ to high‐magnitude seismic sequences in the last few years. Our findings will be a necessary step forward in defining the active processes in the Earth's interior and in defining the seismic risk of the area. The combination of passive and active seismic data provides a robust image of the deep structure of crust and lithosphereBeneath the N. Apennines, the mantle wedge is located beneath the topography divide, 40 km eastward with respect to previous estimateOnly one third of the Adriatic crust is accreted in the orogenic wedge, while the rest descend down to deeper depth