Active Fault Geometry and Kinematics in Greece: The Thessaloniki (Ms=6.5,1978) and Kozani - Grevena (Ms=6.6, 1995) Earthquakes - Two Case Studies

摘要

Two seismogenic areas in northern Greece are examined as ease studies, in respect to their fault geometry, kinematics and segmentation, and their fault pattern similarities and differences. The first area, the Mygdonia depression, close to Thessaloniki (pop. about 1,000,000) was the site of a Ms = 6,5 earthquake happened in June 1978. The second is the Kozani -Grevena (western Macedonia) area affected by the May 1995, M, = 6.6 shock. Both areas are dominated by typical active normal faults and the surface coseismie ruptures (of 1-10 cm displacement) formed along a main fault strand (-10 to 20 km respectively) and propagated on various other synthetic, antithetic, sympathetic and scissors faults. Main fault ruptures length are short in relation to released seismic moment, while fault segments and ruptured segments do not always match. The rupture pattern in both cases looks very similar. This enhances the hypothesis of multifractured type areas, which seem to dominate active tectonics in Greece. In such multifractured areas it is difficult to apply a particular segmentation model, since there seem to be many different fault strands quiescent during recent times, as shown by palaeoseismological trenching.