M. Sorriso-valvo et al., Mass-movement, geologic structure and morphologic evolution of the Pizzotto-Greci slope (Calabria, Italy), GEOMORPHOLO, 30(1-2), 1999, pp. 147-163
Deep-seated mass-movements of different types affect the Pizzotto-Greci slo
pe in northwest Calabria, Italy. The slope is carved out of phyllitic rocks
capped by gneissic layers. Its geological structure is extremely complicat
ed by tectonic structures that pervasively cross the slope transversely and
downslope. A large-scale gravitational deformation of sackung type affects
the slope. On the upslope side a debris-flow source area feeds a large fan
constructed by recurrent debris-flow deposits. Aggradation is consequently
occurring along the stream at the base of the slope.
In order to define the internal structure of the slope for a stability slop
e model, geological, geostructural, geomorphological, historical and dendro
geomorphologic studies, as well as direct geotechnical logs and indirect ge
ophysical investigations have been carried out over a two-year project fina
nced by the EC Environment Programme.
The main aspects of the geological and geomorphological studies and some pr
eliminary geotechnical data are presented here, along with a conceptual mod
el aimed at describing the relationships between the mass-movements on the
slope and the construction/destruction stages of the fan at the base of the
slope. The model is based on the assumption that aggradation has a stabili
sing effect on the slope, thus debris-flow activity is reduced and, consequ
ently, destruction of the fan occurs, bringing the slope again towards unst
able conditions. The reactivation of mass-movement, however, leads to the r
econstruction of the fan and the buttressing effect at the base of the slop
e is restored. Thus, the process is cyclic and self-regulating. (C) 1999 El
sevier Science B.V. All rights reserved.