Coseismic crustal deformation from microseismicity in the Patras area, western Greece

The Patras area lies in the western part of central Greece. It is an area characterized by high seismicity and complex neotectonics. Several devastating earthquakes have occurred in the region since 600 BC. Contemporary crustal deformation is examined in this area using microearthquake data recorded over a lengthy period, during 1983-84, by the Patras Seismic Network, principally, and to a lesser extent by the Volos Seismic Network. The microseismicity (1.8-3.9 M,) defines a zone deepening to the NE, which justifies a possible extension of the Gulf of Corinth major graben towards the Trikhonis Lake to the NW. Spectra of 108 well-located microearthquakes are estimated, using P-waves obtained by selective windowing designed to include only the P-phase; seismic moments in the range 0.3-45.7 X 10 ” N m are obtained, accompanied by estimates of seismotectonic source parameters including source radii, average stress drop and average coseismic slip. Poor correlation is found between seismic moment and magnitude, and the likel