Casagli, Nicola

Catani, Filippo

Pancioli, Valeria

Tofani, Veronica

English

Florence Research

Geophysical Research AbstractsVol. 12, EGU2010-13490, 2010EGU General Assembly 2010© Author(s) 2010Integration of the PSI technique and conventional ground-based methodsfor landslide characterization and monitoring: the case study of SantoStefano d’Aveto; Northern Apennines, ItalyVeronica Tofani, Valeria Pancioli, Filippo Catani, and Nicola CasagliUniversity of Florence, Earth Sciences Department, Firenze, Italy (veronica.tofani@geo.unifi.it)Santo Stefano village is located in the Northern Apennines (Italy) and is built up on an ancient landslide, definedas a complex phenomenon that is an earth rotational slide evolving into a flow. The landslide has an extension of1,3 km2 and a volume of about 10 million of m3. The landslide can be defined as active and according to Cruden& Varnes (1996) nomenclature the velocity range from very slow to extremely slow. The landslide poses and highrisk to the buildings and infrastructures causing extensive direct damages.The Santo Stefano d’Aveto village is located inside a glacial valley made mainly of ophliotic rocks, sandstonesand marls and filled with glacial deposits. The landslide occurred in the glacial deposits composed of debris in asandy-clayey matrix.Santo Stefano d’Aveto landslide has been monitored through radar interferometry, in particular with the PS-InSARtechnique (Ferretti et al., 2001) and through ground-based instruments such as inclinometers and piezometers.The PS-InSAR analysis has been performed using ascending SAR scenes and descending SAR scenes fromERS-1/-2 (1992-2001), and ascending and descending SAR scenes from ENVISAT (2002-2008). All the datasetshave been processed in the advanced mode APSA that means for each PS has been provided deformation timeseries relative to a reference date (zero). The target points within the Santo Stefano landslide have a high density.In general for all the analysed datasets it has been observed a decrease of velocity from upslope portion to thedownslope one of the landslide. The maximum velocity recorded in the ERS dataset is around 38 mm/y, while themaximum velocity recorded in the ENVISAT dataset is around 20 mm/y.The APSA analysis has provided information about the temporal evolution of target points. Both the majority ofERS and ENVISAT time series have shown a seasonal trend related to the variation of the water table level, whichrises during rainfall season and decreases during dry season. The time series analysis show that the landslidedeformation pattern is strongly controlled by the pore water pressure condition as demonstrated by the piezometricmeasurements. As usual an increase of water pressure condition led to a decrease of shear strength of the soilcausing an increase of movement.Six inclinometric instruments have been installed in 2001 and measurements have been acquired until 2006. Acomparison between the deformation measured by the PS techniques and the inclinometric acquisitions has beenperformed examining the velocity measurements along the same line of sight. In particular in order to performthe comparison, the displacements of the inclinometers, taken along the maximum slope angle direction havebeen plotted along the line of sight of the satellite. The results show that the displacements measured by the twodifferent type of techniques are consistent.The PSI analysis performed has contributed to a more in depth investigation of the phenomenon, in particular thePS measurements and geomorphologic interpretation have allowed to redefine better the boundaries of landslideand the state of activity while the time series analysis has allowed to better understand the deformation pattern andits relations with the causes of the landslide itself.Once the relationship between actual displacements vectors (measured by in-situ instrumenation) and l.o.s.components is known, the APSA analysis can provide a much larger dataset on ground movement allowing abetter modelling of the surface displacements field.

Integration of the PSI technique and conventional ground-based methods for landslide characterization and monitoring: the case study of Santo Stefano d&#8217;Aveto; Northern Apennines, Italy

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Integration of the PSI technique and conventional ground-based methods for landslide characterization and monitoring: the case study of Santo Stefano d’Aveto; Northern Apennines, Italy

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Florence Research

Integration of the PSI technique and conventional ground-based methods for landslide characterization and monitoring: the case study of Santo Stefano d&#8217;Aveto; Northern Apennines, Italy

Abstract

Similar works

Full text

Available Versions

Florence Research

Integration of the PSI technique and conventional ground-based methods for landslide characterization and monitoring: the case study of Santo Stefano d’Aveto; Northern Apennines, Italy