Integration of persistent scatterer interferometry and ground data for landslide monitoring: the Pianello landslide (Bovino, Southern Italy)

A Refice,M N Miccoli,F Bovenga,G Pasquariello,A Fiore,L Spalluto,P Muzzicato,R Nutricato,D O Nitti

doi:10.1007/s10346-018-01124-0

Abstract

We present an example of integration of persistent scatterer interferometry (PSI) and in situ measurements over a landslide in the Bovino hilltop town, in Southern Italy. First, a wide-area analysis of PSI data, derived from legacy ERS and ENVISAT SAR image time series, highlighted the presence of ongoing surface displacements over the known limits of the Pianello landslide, located at the outskirts of the Bovino municipality, in the periods 1995–1999 and 2003–2008, respectively. This prompted local authorities to install borehole inclinometers on suitable locations. Ground data collected by these sensors during the following years were then compared and integrated with more recent PSI data from a series of Sentinel-1 images, acquired from March 2014 to October 2016. The integration allows sketching a consistent qualitative model of the landslide spatial and subsurface structure, leading to a coherent interpretation of remotely sensed and ground measurements. The results were possible thanks to the synergistic operation of local authorities and remote sensing specialists, and could represent an example for best practices in environmental management and protection at the regional scale.

Highlights

The Daunian Apennines in Apulia (Southern Italy) are intensely affected by land instability, mainly related to very shallow soil slips and to relatively deeper (> 20 m) landslides (Ciaranfi et al 2011; Cotecchia et al 2015; Cotecchia et al 2016, among others)
We set for the used probes an empirically assessed accuracy of about 7 mm per 30 m of casing, to what proposed in the recent literature for analogous probes (e.g., Stark and Choi 2008)
A first investigation, through analysis of legacy ERS and ENVISAT-derived PS data performed over large areas, highlighted the local presence of moving PS points, indicating active deformation within the limits of the known Pianello landslide, in the outskirts of the town of Bovino, in northern Apulia region (Southern Italy)

Summary

Introduction

The Daunian Apennines in Apulia (Southern Italy) are intensely affected by land instability, mainly related to very shallow soil slips and to relatively deeper (> 20 m) landslides (Ciaranfi et al 2011; Cotecchia et al 2015; Cotecchia et al 2016, among others). The dominant movement takes place along shear surfaces bounding the moving mass (e.g., Ciaranfi et al 2011) This kind of landslide typically starts as a roto-translational slide evolving, after the post-failure stage, into a flow having slow velocity (≲ 1.6 m/year; Cruden and Varnes 1996), occasionally reaching moderate velocities (~ 13 m/month) during main re-activations (e.g., Parise et al 2012; Cotecchia et al 2015). The rate of displacements follows seasonal trends, being lowest in summer and highest in late winter/early spring, when very high piezometric heads are recorded down to large depths (Cotecchia et al 2014)

Results

Discussion

Conclusion