Late Quaternary faulting in Thessaly, Greece

The whole Aegean Region is at present undergoing a N-S crustal stretching. During the last few years also in Thessaly (central continental Greece) specific geological, structural and morphological investigations have emphasised the existence of several recent and active faults. Though still in progress, a multi-approach neotectonic research has been carried out and almost completed. The first undertaking was a structural survey in order to detect and map all major and minor tectonic structures existing in the area; the main result is a structural map of Thessaly. Second step was to reconstruct the tectonic stratigraphy at least from Pliocene to Present and compare it with the evolution of the Aegean region. The existence of two tectonic phases has been documented: an older one during Pliocene-Lower Pleistocene? with a NE-SW direction of the sigma3, and a younger phase from Middle Pleistocene to Present with a N-S sigma3 direction. The next step was to detect and separate all faults showing features of recent activity and to understand their geometry and kinematics. For this purpose, a detailed structural and morphotectonic survey at the scale 1:5.000 has been carried out for all these structures which have been recognised both from aerial photos and directly in the field. Most of the faults generated during this tectonic phase are trending E-W to ESE-WNW. Locally, NW-SE or even NNW-SSE structures, inherited from older phases, have been also reactivated. All the faults show clear evidences of recent tectonic activity such as triangular facets, morphological scarps and scarplets, almost unweathered sliding surfaces, uplifted and entrenched young deposits, open fractures and joints as well as outcropping faulting of Late Quaternary sediments. At least two of the faults suffered morphogenic earthquakes in historical times (Sophades, 1954 and Volos, 1980).