Geophysics

Parting the Gulf of Corinth

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Science  12 Jan 2001:
Vol. 291, Issue 5502, pp. 213
DOI: 10.1126/science.291.5502.213a

The Aegean region has one of the highest rates of seismicity and extension in Europe. It consists of three major rifts: the North Aegean trough, the Evvia graben, and the Corinth rift. The region is actively deforming between the India-Eurasia collision zone (represented by the North Anatolian fault that cuts across Turkey and connects to the northern Aegean region) and the Africa-Eurasia collision zone (represented by the Hellenic Arc subduction zone that connects to the southern Aegean region). Previous studies in the Gulf of Corinth, the main part of the Corinth rift, indicate that the deformation measured from geodetic data does not match that determined from seismic data.

Briole et al. have completed an extensive global positioning system (GPS) campaign from 1990 to 1995. They have measured about 14 millimeters per year of extension in the western gulf and about 10 millimeters per year in the eastern gulf. Their model accounts for the deformation by requiring most of the slip to occur on low-angle normal faults within a more narrowly defined vertical depth along the rift margins than that used in previous models. These normal faults would account for the seismicity, while aseismic creep in the shallow crust (due to water and sediments in the central gulf) and in the deeper crust (due to a decollement at the brittle-to-ductile transition zone of the crust) would explain the additional geodetic deformation. Thus, while the gulf is rifting noisily by normal faulting in medium-sized earthquakes, it also is extending quietly by creeping near the surface and at depth. — LR

J. Geophys. Res.105, 25605 (2000).

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