On the spatial distribution of seismicity and the 3D tectonic stress field in western Greece

Publication date: Available online 23 March 2016 Source:Physics and Chemistry of the Earth, Parts A/B/C Author(s): Ioannis Kassaras, Vasilis Kapetanidis, Andreas Karakonstantis We analyzed a large number of focal mechanisms and relocated earthquake hypocenters to investigate the geodynamics of western Greece, the most seismically active part of the Aegean plate-boundary zone. This region was seismically activated multiple times during the last decade, providing a large amount of enhanced quality new information that was obtained by the Hellenic Unified Seismological Network (HUSN). Relocated seismicity using a double-difference method appears to be concentrated above ∼35 km depth, exhibiting spatial continuity along the convergence boundary and being clustered elsewhere. Earthquakes are confined within the accreted sediments escarpment of the down-going African plate against the un-deformed Eurasian hinterland. The data arrangement shows that Pindos constitutes a seismic boundary along which large stress heterogeneities occur. In Cephalonia no seismicity is found to be related with the offshore Cephalonia Transform Fault (CTF). Onshore, N-S crustal extension dominates, while in central and south Peloponnesus the stress field appears rotated by 90˚. Shearing-stress obliquity by 30˚ is indicated along the major strike-slip faults, consistent with clockwise crustal rotation. Within the lower crust, the stress field appears affected by plate kinematics and distribut...
Source: Physics and Chemistry of the Earth, Parts ABC - Category: Science Source Type: research