Geometry and kinematics of active faults and their seismotectonic significance in the western Corinth-Patras rift (Greece)

Abstract

The western part of the Corinth-Patras rift is formed in an area which is being uplifted. Rifted domains have subsided relative to the adjacent areas in NW Peloponnesus and Sterea Hellas, but subsidence rates rarely exceed uplift rates. Extension is mainly accomplished by WNW-trending active faults with lengths up to 25 km. Most of these faults show an along-strike segmentation and often terminate against transfer faults. Displacement analysis, along 170 mesoscopic faults and 36 mappable faults, has been carried out to assess slip rates and to estimate the magnitudes and recurrence time intervals of earthquakes occurring along them. Earthquake magnitude ranges between 5 and 6.7. Only eight faults appear to be capable of producing earthquake magnitudes larger than 6. Recurrence times of these large earthquakes vary between 80 and 1690 years. Upper crustal deformation in the western Corinth graben can be described by six large asymmetric grabens which are inferred to bottom out to a N-dipping curved ramp. The asymmetric shape of most WNW-trending rifts in the Hellenic peninsula, including the Corinth-Patras rift promotes the simple shear model of extension against the pure shear model in the upper crustal layer.