Active fault geometry and kinematics in Parnitha Mountain, Attica, Greece

摘要

The Parnitha mountain range lies between two Quaternary rift systems in central Greece: the Gulf of Corinth Rift and the Gulf of Evia rift. We suggest that the range was formed by footwall uplift on active normal faults striking WNW-ESE and NE-SW. We investigated the scarp appearance, geometry and slip rates of three normal faults bounding this mountain range by field mapping at 1:5000 scale. Active faults studied include the 8.5 km long Fili Fault, the 4.7 km long Maliza Fault and the 4 km long Thrakomakedones Fault. We calculated comparable mean slip rates for all mapped faults (Fili: 0.18 mm/yr, Avion: 0.2 mm/yr, Thrakomakedones: 0.24 mm/yr); however, we suggest that the WNW-ESE structures are more active during the Late Quaternary because of abundant field evidence of recent movements along slip surfaces (fresh basal stripes and slickenlines). In addition, stress axes analysis shows a N7°E-N25°E (NNE-SSW) oriented, extensional stress field, which is compatible with the focal mechanism of the Athens 1999 earthquake. The fault-slip data from the Parnitha faults show orientations similar to other low-strain areas in central Greece, such as the Gulf of Evia Rift to the north. Our slip rate estimates may explain the low recurrence of large earthquakes in Attica as opposed to high slip rate areas in central Greece such as the neighbouring Gulf of Corinth.