Seismicity of Greece

It is well known that the Aegean and surrounding area, which includes mainland Greece, the Aegean Sea, Albania, S. Yugoslavia, S. Bulgaria, W. Turkey and part of the Northern Eastern Mediterranean, is seismically the most active region in the whole Mediterranean and in the whole West Eurasia. This region is a part of the collision zone between the Eurasian and the African lithospheric plates but its present tectonic activity is much higher than in other regions of the same zone.
The most prominent morphological features of tectonic origin in the Aegean and surrounding area from south to north are: the Mediterranean ridge (or chain), the Hellenic trench, the Hellenic arc and the northern Aegean trough.
The Mediterranean ridge is a submarine crustal swell that extends from the Ionian Sea to Cyprus and parallels the Hellenic trench.
The Hellenic trench consists of a series of depressions with depth to about 5km. It parallels the Hellenic arc and includes some linear trenches, as are the Pliny and Strabo southeast of Crete and the Ionian trench.

The Hellenic arc is formed by the outer sedimentary arc, a link between the Dinaric Alps and the Turkish Taurides, and the inner volcanic arc, which parallels the sedimentary arc at a mean distance of about 120 km. The volcanic arc consists of several volcanic islands and includes andesitic active volcanoes (Methana, Santorini, Nisyros) and solfatara fields. Between the sedimentary and the volcanic arc is the Cretan trough with depth to about 2000 m.
The most interesting feature of the northern Aegean is the northern Aegean trough with depth to about 1500 m. Its extension to northeast is probably the small depressions of the Marmara Sea.
The distribution of the epicenters of the large shallow shocks (h < 60 km) form several seismic zones. The external seismic zones form a continuous large seismic belt along the external (convex) side of the Hellenic arc, and its extension along the western coast of central Greece, Albania and Yugoslavia. All other zones constitute the internal seismic zones, which have an almost east-west direction.
The spatial distribution of the foci of the intermediate focal depth (70km