Block Kinematics, Interseismic Coupling and Fault Slip Rates in the Aegean Region From GPS and Earthquake Slip Vector Data: 1. Upper Plate Structures

Abstract We represent the active deformation of the Aegean region with an elastic‐kinematic block model composed of a finite number of rotating crustal blocks whose boundaries coincide with major active structures. A total of 832 GPS velocities and 146 earthquake slip vectors were inverted to provide estimates of block rotations and interseismic locking on block‐bounding faults so as to best reproduce the observed deformation field. Our regional model allowed us to derive a self‐consistent set of geodetic slip rates for upper plate faults and the Hellenic subduction system, the results of which are presented in a companion paper, and to determine their corresponding slip rate deficits (geodetic moment accumulation rates). Most of the faults show either full or high levels of locking, with some exhibiting significant fault slip rate deficits, and only a few displaying very low or no coupling. Model results indicate that crustal blocks in the SE Aegean‐SW Anatolia rotate counterclockwise, whereas those in central‐NW Greece rotate clockwise. Between these domains, blocks move rapidly southwestward with trenchward‐increasing velocities. The observed block motions in the Aegean reflect the combined influence of several large‐scale tectonic processes that shape the present‐day geodynamics, including the westward tectonic escape of Anatolia, rapid slab rollback and trench retreat along the Hellenic Arc, and along‐strike variations in the Nubia‐Eurasia plate boundary.