The PRIN2020 Project aimed at investigating the fault complexities in active thrust systems like those of the Northern Apennines and Southern Alps (NASA; Figure 1), and at quantifying their consequences on standard and pioneer practices of seismic hazard assessments. We established two distinct, but concatenated, major goals. Firstly, we aimed at better defining the 3D geometry and the kinematics of the thrust systems. This goal can be reached by improving our knowledge on the internal fault hierarchy and earthquake occurrence at specific fault segments, based on a multidisciplinary approach, in which geological, geophysical, remote sensing, seismological, palaeoseismological, geodetic, and morphotectonic datasets are integrated and critically confronted among researchers with...