THE MAY 13, 1995, KOZANI-GREVENA (NW GREECE) EARTHQUAKE - SOURCE STUDY AND ITS TECTONIC IMPLICATIONS

At 08:47 GMT, on May 13, 1995, a strong earthquake of M-s, = 6.6 occur red in the NW part of Greece (Western Macedonia) and caused serious da mage in the Kozani and Grevena prefectures, but fortunately no fatalit ies. The maximum observed macroseismic intensity was IX + of the Modif ied Mercalli scale. The main shock was preceded by several foreshocks and followed by intense aftershock activity lasting several months. Th e Institute of Geodynamics of the National Observatory of Athens, in o rder to monitor and study the aftershock activity, installed a seismic network of nine (9) stations operated for a period of 50 days. Thousa nds of aftershocks were recorded. Based on the analysis of recorded da ta, a NE-SW trending zone dipping NW is defined. In the field a surfac e rupture of normal slip was observed, following a NE-SW direction for a length of 8 km with a 4 cm down throw of the NW area. This break wa s located along a pre-existing minor normal fault, while a main fault system exists 10 km to the SE. The focal mechanism of the main shock s hows normal faulting, which is in agreement with the field observation s. Moreover focal mechanisms of several well defined aftershocks were computed, showing various types of faulting. (C) 1998 Elsevier Science Ltd. All rights reserved.