Analysis of recent ground subsidence in the Sibari plain (Italy) by means of satellite SAR interferometry-based methods

Abstract

This work attempts to map recent land subsidence on the Sibari plain in Calabria region (Southern Italy), by exploiting vertical velocity values and time series of persistent scatterer interferometry (PSI) synthetic aperture radar (SAR) data acquired in the period 1992–2011 by different satellite systems.

After reviewing other sources and rates of subsidence recorded by previous works since the beginning of the Holocene, this paper presents the spatial distribution of the current settlement rates showing that subsidence is due to the compressible alluvial sediments of the plain, but that in recent times it is mostly due also to human activities. In fact, according to the most recent monitoring period (2009–2011), downward motion rates are recorded as being only localized within site-specific industrial areas, such as the ‘Sibari Lakes’ nautical and residential centre and Corigliano Calabro Industrial Zone. The temporal analysis of persistent scatterers (PS) time series, carried out through the PS-Time program, adds further useful information, finally highlighting that, in these areas, subsidence has positively decreased or stabilized from the second semester of the year 2010.

This work shows that PSI measurements provide support in the quantitative evaluation of known subsidence process and that the analysis of time series allows effective detection of the temporal evolution trends of the phenomenon, such as changes or deceleration in displacement rates, not otherwise visible by merely considering the average velocity.

Acknowledgements

The PS time series were elaborated by means of the PS-Time tool, which is a stand-alone application developed by Mr Berti and colleagues (Berti et al., 2013), available at: http://www.bigea.unibo.it/it/ricerca/pstime.

Additional information

Funding

This work was carried out within the SAFER (Services and Applications For Emergency Response) project funded by the European Commission (EC GMES FP7 initiative; Grant Agreement no. [218802]). Radarsat 1/2 data were provided by the ESA-managed GSC-DA, funded by the FP7/2007–2013 under EC-ESA Grant Agreement no. [223001], and were processed by e-GEOS with the PSP-DIFSAR technique in the framework of the SAFER project. ERS PSI data were made available through the PST-A (Piano Straordinario di Telerilevamento Ambientale) project and the WMS service of the Italian Ministry for the Environment, Land and Sea.