Deep seated gravitational slope deformations in active tectonics areas of the Umbria-Marche Apennine (central Italy)

The present work illustrates three cases of deep-seated gravitational slope deformation (DSGSD) in an active tectonic area in the Umbro- Marchean Apennines. The area was affected by an intense seismic crisis that lasted eight months in 1997-98. The correct genetic attribution of the studied phenomena was possible only through the geomorphologic interpretation of numerous data acquired through geotechnical and geophysical surveys and instrumental monitoring. Two phenomena are found along the edge of the tectonic basin of Colfiorito, and the third is situated along the Chienti valley, at the foot of a wide versant on the left bank of the river. The studied phenomena involve the calcareous-marly and marly lithotypes of the «Umbria-Marche Sequence», affected by relevant tectonic dislocations: thrusts and normal and reverse faults. The epicentres of major earthquakes were aligned along the direct and reverse faults which are considered «capable».