GNGTS 2013 - Atti del 32° Convegno Nazionale

AF index of the Catona Fiumara approaches to 50, indicating no asymmetry, thus this index has been evaluated for the 10 sub-basins. Results show that both the sub-basins on the left side and that on the right side of this fluvial basin are asymmetric due to the differential uplift of specific sectors. Re index highlights an elongated shape of the Catona Fiumara basin indicating an immature stage. Hypsometric curve and SL index evaluated for this river highlight uplifted and rejuvenated sectors where it meets the Santa Eufemia Fault and Cittanova Fault. Further- more, hypsometric curves of the sub-basins 1, 8 and 10 evidence a localized uplift affecting the northern sector of the Catona Fiumara that lies on the Scilla Fault footwall (Fig. 3). AF and T indexes of the Petrace Fiumara indicate that the basin is asymmetric and the trunk channel flows close to the left side of the watershed (Tab. 1). Hypsometric curve shows a mature stage of this river with a rejuvenated sector in proximity of the Cittanova Fault where SL index shows localized uplift. Conclusions. Geomorphologycal and morphometrich analyses performed on the Catona Fiumara and Petrace Fiumara highlight that their drainage is perturbed by recent tectonic movements. In particular localized uplift causes rejuvenation of specific sectors where drainage is trying to restore equilibrium. The Petrace Fiumara evolution seems to be controlled principally by the Cittanova Fault whose recent activity produced a depocentre in the northern sector of the basin. The Catona Fiumara mainly suffers the activity of the Santa Eufemia Fault and Scilla Fault and also of the Cittanova Fault. In particular the counterclockwise rotation and the rejuvenation of part of the basin can be ascribed to the recent activity of the Scilla Fault, which caused local uplift and tilting. This is shown by the rotation of sub-basins 1 and 4 occurred through fluvial captures, as testified by several suspended valleys (Fig. 3). Our results contribute to constrain the seismotectonic setting of southern Calabria supporting the hypothesis that the normal faults intercepting the drainage network have Holocene activity and they can have slipped during recent earthquakes. Fig. 3 – A) Google Earth image showing the track of the Scilla Fault (SF) and the rotation of the sub-basin 1 main branch because of capture; the topographic profile shows a suspended valley testifying the original northwestward drainage of the sub-basin 1 main branch; B) sketch map of the Catona Fiumara sub-basins, ellipse shows the uplifted sector due to the Scilla Fault activity, rectangle is the inset of A; C) Hypsometric curve of sub-basin 1 showing rejuvenated sectors on the footwall of the Scilla Fault (SF) and Santa Eufemia Fault (SEF). 107 GNGTS 2013 S essione 1.1