GEOMETRY OF CONTINENTAL NORMAL FAULTS - SEISMOLOGICAL CONSTRAINTS

Teleseismic body waves from large earthquakes are used to study the do wndip geometry of continental normal faults in the Aegean. Waveform mo deling techniques together with rigorous statistical tests are applied to put firm bounds on the amount of downdip curvature of these faults and the role of coseismic slip on a basal detachment. Synthetic model ing shows that good azimuthal station coverage and inclusion of SH wav es are necessary to resolve fault curvature. The data indicate rupture s of the Aegean events occurred on planar faults extending across the entire brittle portion of the crust. No seismogenic low-angle detachme nt faulting at the base of the upper crust was detected for these even ts. Decoupling of the brittle upper crust from the plastic lower crust probably occurs aseismically in a ductile fashion.