The evolution of the Gulf of Corinth (Greece): an aftershock study of the 1981 earthquakes

A preliminary study of the aftershocks of three earthquakes that occurred near to Corinth (Greece) in 1981 is combined with observations of the morphology and faulting to understand the evolution of the Eastern Gulf of Corinth. The well located aftershocks form a zone 60km long and 20km wide. They do not lie on the main fault planes and are mostly located between the north-dipping faulting on which the first two earthquakes occurred and the south-dipping faulting associated with the third event. A cluster of aftershocks also lies in the footwall of the eastern end of the south-dipping fault of the third event

Seismicity, normal faulting, and the geomorphological development of the Gulf of Corinth (Greece): the Corinth earthquakes of February and March 1981

International audienceThree major destructive earthquakes of M~ 6.7, 6.4, 6.4 occurred in the eastern part of the Gulf of Corinth in February' and March 1981. Associated normal faulting was observed on both the north and the south sides of the (iulf. Examination of teleseismic, local seismic, surface faulting and geomorpbological data sugge.,ts that the first and second of these shocks activated major north-dipping normal faults. These faults control the topography and bath?metr> and are related to the recent uplift and subsidence of the coastline. It is probable that the first earthquake occurred on a fault which outcrops underwater and the second on a fault which is ~isible on land. It appears that the third shock activated an antithetic normal fault dipping southwards on the north side of the Gulf and that the overall structure of the Gulf of Corinth graben is asymmetric. The northern antithetic fault clearly demonstrates the geomorphological changes associated with developing young normal faulting. In addition, we suggest that observations of recent coastline movement provide a powerful tool for identifying major active fault systems and predicting their historical role in the paleogeography of an area

Microearthquake seismicity and active tectonics of northwestern Greece

We carried out a microearthquake survey lasting for six weeks in northwest Greece using 18 portable seismograph stations to examine a region in which normal and thrust faulting have been reported in close proximity to one another. With this array we located 148 events and determined fault plane solutions for eight events using only rays radiated upwards. The seismicity of the region is diffuse with events extending to depths of nearly 30 km, and there is a minimum in activity near a depth of 15 km. The fault plane solutions exhibit a wide spectrum of fault types and orientations and are not consistent with simple zones of shortening or extension. Neither tractions applied to the edges or bottom of the region nor deviatoric stresses that compensate for lateral variations in crustal thickness can account for the variety of fault plane solutions. We think that the complicated behavior is a manifestation of inhomogeneous deformation due, at least in part, to a pre-existing complicated juxtaposition of structures and formations