Regional focal mechanisms in the Aegean area determinded by waveform modeling and their Tectonic imp
Focal mechanism parameters of earthquakes with magnitude Mw>5.0 and shallow focal depth (h <40 Km) from Greece and its surroundings have been estimated using the technique of far-field body waveform modeling. We inverted P- and SH- waveforms recorded at stations of the Global Seismograph Network (GSN), with epicentral distances 30o<Δ<90o, using a point source approximation. First motion polarities of P- waveforms recorded at lower epicentral distances were complementary used in order to better constrain the focal mechanisms.
The analysis of these data, combined with the fault plane solutions of 107 earthquakes taken from the literature, can be summarized as follows:
· Low angle thrust faults dipping to the NE dominate along the coasts of Albania and NW Greece.
· The southwestern part of the Hellenic arc is characterized by low angle thrust faulting, in some cases combined with a significant strike slip motion, and reverse faults as well.
· The fault plane solutions of 6 earthquakes (Mw>5.4) that occurred in western Peloponnese show strike-slip motion along nearly vertical fault planes.
· The widespread strike-slip motion observed in the northern Aegean Sea, which is due to the splay of the North Anatolian Fault into several strands as it enters the Aegean, extends to the south up to the N38o parallel.
· East-west extension dominates along a narrow zone following the Dinarides-Hellenides mountain belt up to the Rhodes Island in the eastern Hellenic Arc, while continental Greece and southwestern Turkey are characterized by normal faulting along ~E-W trending planes.
