New geodetic constraints on the role of faults and blocks versus distributed strain in the Nubia-Arabia-Eurasia zone of active plate interactions

We present a broad view of present-day motions and deformations derived from uniform processing of GNSS observations within the Nubia-Arabia-Eurasia zone of plate interaction. The new observations we present provide a similar to 29% increase in the number of velocity determinations, a reduction in average station spacing from similar to 76 km to similar to 39 km, and an improvement in velocity uncertainties (for <1 mm/year), from 180 to 578 sites compared to our prior published solution (Reilinger et al., 2006). We use these new constraints to better evaluate the role of faults and blocks in controlling the character of continental deformation within the zone of plate interactions. Simple elastic block models show that internal deformation of the region occurs in large part on mapped, seismically active fault systems, indicating elastic behavior of the seismogenic crust (above similar to 15 km). For example, eastern central Anatolia, an area of > similar to 126,000 km(2), bounded by the North and East Anatolian Faults exhibits internal velocity differences of <0.5 mm/year, indicating strain rates of < similar to 1.5 nanostrain/year. Geodetically constrained fault slip rates obtained from this simplified approach are comparable to geologic rates, indicating that major faults have controlled the recent geologic evolution of the region (i.e. 5-10 Myr). The pattern of present-day deformation, including increasingly fast motions towards the Hellenic trench, and the roughly simultaneous opening of all the major Mediterranean basins in the early Miocene with the slowing of the Nubia-Eurasia convergence, support conceptual models that foundering and rollback of the subducted Nubian slab beneath the Aegean is the primary mechanism responsible for present-day motion and internal deformation of the Anatolian-Aegean region.