North Aegean crustal deformation: An active fault imaged to 10 km depth byreflection seismic data

Three multichannel seismic profiles imaged a normal fault to at least 10 km depth in the North Aegean Trough and Thermaikos basin. The fault is active and recent, forming a scarp at sea bottom and crossing the Quaternary delt aic front on the northern slope of the trough controlled to the south by th e North Anatolian fault. Prestack depth migration imaged the fault as a sei smic reflector cutting steeply across the sedimentary rocks and flattening in the basement. From the seismic image, the N100 degrees E strike of the f ault scarp, and the orientations of the three profiles, the true fault dip is constrained to an average 20 degrees in the basement, a low-angle dip. T he throw and age estimated from the geometry in the sedimentary rocks docum ent recent onset of the motion that must have occurred at a high rate. Both the direction and the rate of slip are consistent with the instantaneous m otion as measured by space-based geodesy, which shows the fault to be formi ng by pure normal slip. Large earthquakes that have occurred in the basin m ay relate to such normal faults, whereas the North Anatolian fault,vith its current strike-slip earthquakes appears to slip here under low resolved sh ear stress.