Microseismicity and focal mechanisms at the western termination of the North Anatolian Fault and their implications for continental tectonics

For seven weeks, a temporary network of 68 seismological stations was opera ted in Central Greece, in the region of Thessaly and Evia, located at the w estern termination of the North Anatolian Fault system. We recorded 510 ear thquakes and computed 80 focal mechanisms. Seismic activity is associated w ith the NE-SW dextral North Aegean Fault, or with very young E-W-striking n ormal faults that are located around the Gulf of Volos and the Gulf of Lami a. The important NW-SE-striking faults bounding the Pilion, or the basins o f Larissa and Karditsa, are not seismically active, suggesting that it is e asier to break continental crust, creating new faults perpendicular to the principal stresses, than to reactivate faults that strike obliquely to the principal stress axes.