Seismogenic sources potentially responsible for earthquakes withM≥ 6 in the eastern Southern Alps (Thiene-Udine sector, NE Italy)

New geomorphological and structural data permitted to define the active faulting framework of eastern Southern Alps (NE Italy). All the active faults detected in the investigated area are segments of the complex thrust system,which has been responsible for the latest building the Eastern Southalpine chain (ESC). Geomorphological investigations were performed to the surficial traces of recent fault activity, generally represented by gentle scarps uplifted palaeolandscapes of Quaternary age with the flat and lower areas of the and Friulian plains. Surficial and subsurficial data (the latter from reflection seismic) available for the investigated faults indicate that the thrusts have been responsible the displacement of the entire wedge of Quaternary deposits. In the western sector of investigated area, the six recognized fault segments represent portions of a 100-km-long system, at the boundary between the Alpine relief and the plain areas. In the eastern, active tectonics is the result of parallel thrust segments, located both in the Alpine area and in the Friulian plain. The 3-D geometry of the active thrust segments has derived from new structural surficial surveys and the interpretation of reflection seismic for a total length of 1700 km. On this basis, we defined the geometry of 10 seismogenic whose dimensions are consistent with the occurrence of earthquakes with M ≥ 6. The between the source geometry and the highest intensity data point distribution of historical earthquakes has permitted to make hypotheses on the association of past seismic to specific seismogenic sources. This procedure indicated that no large historical events be attributed to three sources (Montello-Conegliano, Arba-Ragogna, Medea). This may an elapsed time since the last activation of more than eight centuries, based on the of the historical catalogues. The available data define, therefore, sources (and areas) for which a high level of seismic hazard may be invoked.