Surface and deep displacements evaluated by GPS and inclinometers in a clayey slope.

The continuous deformations of two landslides of a clayey slope of the Italian Southern Apennines cause damage to buildings and infrastructures. In 2004, eleven inclinometer casings were installed to monitor them. In 2006, fixed-in-place probes with continuous data acquisition were installed in two of those casings, in correspondence to the detected slip surfaces. In 2010, such probes went out of use, thus were removed and periodical measurements restarted. The validity of the interpretation of previous localized measurements could thus be ascertained. In 2006, GPS permanent and non-permanent stations had also been installed. By taking into account a possible mechanism of interaction soil-GPS station, displacements very close to those obtained by nearby inclinometers with fixed casing tip are obtained. Depending on its particular properties, one of the landslides undergoes uniform displacements in each transversal section of the channel. So, GPS data can also give useful information on the movement of the whole section.