GPS-derived motion of the Adriatic microplate from Istria Peninsula and Po Plain sites, and geodynamic implications

We studied the motion of the Adriatic microplate using Eurasian-referenced GPS-derived velocities from Istria Peninsula (Slovenia, Croatia) and Po Plain (Italy) sites and earthquake slip vectors around its edges from a Regional Centroid Moment Tensor catalogue. We explored kinematic parameters by inverting GPS velocities using a variety of site combinations and comparing results. Our best-fitting GPS Adria–Eurasia angular velocity vector (Euler pole) comes from 7 Istria Peninsula (Slovenia, Croatia) and 10 Po Plain (Italy) sites; it locates at 45.03°N, 6.52°E, with a 0.297 ± 0.116°/Myr counterclockwise rotation rate. This new GPS-derived pole locates and overlaps with our earthquake slip-vector-derived pole. An Adriatic microplate interpretation is at odds with Neogene geologic features that indicate recent convergence across the Apennines and Alps. The neotectonics–geology mismatch probably signals the recent birth of the Adria microplate upon termination of the Nubia–Eurasia Alpine collison and Adria slab break-off beneath the Apennines.