MORPHOTECTONIC CHARACTERISTICS OF THE UMBRIA-MARCHE APENNINES

Abstract

The morphostructural pattern of the Umbria-Marche Apennine is the result of successive deformational events dating back to the Tortonian. These events were compressive between part of the Tor­tonian and the Middle Pliocene yielding folds, break-thrusts, and overthrusts associated with trascurrent faults. During the Quater­nary, the area underwent tensional stress, which was responsible for the present morphostructural configuration. Among the numerous normal faults present, those with an Apenninic direction, which cut the older fold structures at d.ifferent angles, are particularly impor­tant. These are related to tensional processes connected with the opening of the Tyrrhenian Sea, and appear to be stili active, as the re­cent seismic events from the Norcia area indicate.