Greek tectonics and seismicity

Abstract

The validity of existing tectonic models for the area of Greece is examined in the light of the new recalculated parameters for earthquakes of the region (Makropoulos and Burton, 1981). Relocated hypocentral positions are extracted from the catalogue to form radial and vertical distance-depth cross-sections centred on a reference point near the mid-point of the Aegean Volcanic arc, and these are used to form a three dimensional topography of the base of earthquake occurrence below 60 km. Isodepth maps are extracted from this topography as both three and two dimensional map presentations. These maps reveal several significant features of deep-seated tectonic processes in the region. Isodepths exceeding 150 km are seen in the northwest Aegean, and these are more closely linked to the Sporadhes and Gulf of Thermaicos, rather than the North Aegean trough. The 150 km isodepths are also seen in the northeast Aegean straddling the Dardanelles; in the northeastern part of the Peloponnesus, Gulf of Saronikos and eastern Gulf of Corinth in the southern Peloponnesus towards Crete; and extending from north of Kos to south of Rodos. The largest extent of deepest activity is seen south of Rodos and this continues towards southwest of Turkey. The subduction zone of the Hellenic arc is clear, but smooth Benioff zones are not the norm, and these data show that structural complexity is more readily observed. It is concluded that none of the proposed tectonic models completely explain the observed activity over the whole area, and rather than propose yet another model places where further work is still particularly necessary are identified.