A study of the crust stress field for the Aegean region (Greece)

The in situ stress field may be assessed from data such as the fault plane solutions of the earthquakes occurring in the region and by estimation of a stress field compatible with the kinematic behavior of the crust. The regional kinematics may be derived from the velocity field estimated from GPS data and other geodetic observations.In the present work an investigation of the stress field of the Aegean Sea is carried out following two approaches; both use the same tectonic characteristics for the Hellenic region and the same assumptions referring to the mechanical properties of the medium. In the first approach, the yearly rate of the in situ crustal stresses, based on a two-dimensional FE linear analysis, are evaluated solving for the inverse problem, given the GPS observed displacement field for the broader Aegean region. The results have been compared with published papers and with stresses obtained from available focal mechanism solutions.In the second approach the borders of the probable lithospheric micro-plates and the active faults are considered as discontinuities in an elastic half-space representing the earth's crust. The Coulomb stress changes due to the tectonic slip are evaluated, providing an insight of the way these tectonic elements interact. Assuming succeeding activation of the tectonic structures of the region the accumulation of the Coulomb stress changes has been estimated. The accumulated Coulomb shear stress distribution provides a criterion for the selection of the more realistic boundary conditions for the FE modeling. In this respect, the two approaches complement each other and enrich the final picture discussed here.

► The GPS velocity field for the Hellenic region is used as input for the FE modeling.
► The simple FE models used reveal the active tectonic elements of the region.
► The yearly rate of the in situ stress field for the Aegean region is estimated.
► The Coulomb stress analysis supports the importance of the N. Aegean fault system.
► Both FE and Coulomb stress coincide in revealing the shear stress pattern.