Morphotectonics and kinematics along the Tyrnavos Fault, northern Larissa Plain, mainland Greece

The study of the Tirnavos Fault, recently recognized as one of the Late Pleistocene-Holocene faults of the Northern Larissa Plain (Thessaly, Central Greece), is presented. It was formed with an E-W direction during the last and still active tectonic regime activated by a N-S extension. It shows conclusive indications of extremely recent reactivations. In the tectonic frame of the Aegean Region, the Tirnavos Fault is a typical example of active fault few kilometres long (10-12), with small co-seismic displacements (10-20 cm) and characterized by low magnitude seismicity. Accordingly, the investigating approach must differ from the classical palaeoseismological studies performed, for example, in the Basin and Range Province by U.S.-workers. The paper is an attempt to apply both palaeoseismological and kinematic approaches to the study of the Tirnavos Fault in order to determine which is more applicable to this setting. Although emphasis on the kinematic analysis of all the brittle structures and on bedrock scarps has been given, topographic scarps in unconsolidated deposits have been also observed and a detailed morphotectonic mapping carried out. Besides the description of the fault-generated morphologies, other fault-related features such as the damming of a valley, the truncation of a scree fan and the differential erosion of a fan uplifted by the fault, are described and discussed. Due to the complete lack of new chronological data, was not possible to determine the age of any palaeoseismic event. In contrast, it is demonstrated how understanding the kinematics of a fault and of the regional tectonic framework can constrain the timing of fault activity