GPS Monitoring of the Scopello (Sicily, Italy) DGSD Phenomenon: Relationships Between Surficial and Deep-Seated Morphodynamics

The Scopello area, which is located along the north-western Tyrrhenian coastal sector of the
Sicilian chain (Italy), is widely affected by Deep-seated Gravitational Slope Deformation
(DGSD) phenomena, which are mainly the result of a geomorphologic setting marked by the
outcropping of an overthrust plan, limiting a brittle fractured carbonate slab, laid onto a ductile
marly-clayey substratum. Due to the very advanced stage of the deformation phenomena, a
coupled morphodynamic style has established between shallow landslides and DGSD
phenomena, affecting the exhumed ductile substratum and the overlaying rigid dismantled
slab, respectively. A GPS network was realized for monitoring the Scopello landslide,
consisting of 27 vertexes, which were directly cemented either onto rock or debris blocks or
concrete structures rooted on the marly–clayey substratum. The geometry of the network and
the geodetic technique adopted for the GPS signal acquisition allow the survey for a subcentimetric
precision in the positioning of the vertexes. On February 2005 earth-flows and
block/slab-slides movements affected the head sector of the landslide area. The displacements
field, which was derived by comparing the results of a pre- (2004) and a post-event (2005)
GPS surveys, is here analyzed and discussed. On the basis of the observed displacement, the
connection between surficial and deeper ground deformations is confirmed.