Block Kinematics and Interseismic Coupling of Major Subduction Systems in the Central Mediterranean

The Mediterranean is a broad continental deformation zone at the junction between the African and Eurasian plates, where plate convergence is accommodated by distributed faulting, subduction, and transform systems associated with significant seismic and tsunami hazard. Despite the rapid densification of GNSS networks, how plate motion is partitioned into elastic strain accumulation versus aseismic deformation across this region remains unresolved or largely debated, particularly along offshore subduction interfaces, such as the Hellenic and Calabrian subduction zones, and the Dinarides-Albanides thrust front. We present a new regional kinematic block model constrained by an integrated horizontal GNSS velocity field obtained by merging multiple solutions to achieve dense, homogeneous spatial coverage. We implement three-dimensional geometries of the subduction interfaces and thrust systems within a unified block-model framework, allowing surface velocities to be jointly inverted for rigid block rotations, fault slip rates, volcanic deformation, and interseismic coupling (IC), enabling a regional-scale assessment of where elastic strain accumulates along major plate-boundary structures. The model is more detailed in the southern Adriatic and Ionian domains and across the Calabrian and Aegean arcs, including the Albanides–Dinarides margin. We present a first attempt toward a synoptic mapping of interseismic coupling for the Central Mediterranean, providing new insights into strain buildup and associated seismogenic potential of the involved structures. Low but non-zero coupling is inferred along the Hellenic subduction zone beneath Crete, while higher coupling patches are identified along the Cephalonia Transform Fault, and locally along the Albanian and Montenegrin coasts. These regions represent zones of enhanced elastic strain accumulation with implications for future earthquake and tsunami potential. IC along the Calabrian subduction zone is also investigated; however, its spatial distribution remains weakly constrained due to the lack of offshore geodetic observations. Our results highlight the critical role of the poorly defined Nubia–Apulia plate boundary in controlling block kinematics, strain partitioning, and coupling patterns in the Calabrian subduction zone.