Space-borne Synthetic Aperture Radar Interferometry (InSAR) is increasingly used to monitor wide-area to local scale ground motions related to natural and anthropogenic geohazards with up to millimetre accuracy and to generate medium to very high resolution digital elevation models (DEM).
Radar images of the Earth's surface with monthly to daily repeat cycles have been acquired since the 1990s by SAR sensors on board low Earth orbiting satellites, e.g. ERS-1/2 and ENVISAT of the European Space Agency (ESA). These provide unprecedented sources of information that can be used with InSAR techniques for land motion monitoring, geological and topographic mapping.
The EPOM team of BGS has in-house expertise to acquire, process and interpret radar data for applied InSAR research and projects. As part of NERC funded projects we are conducting a feasibility study for deformation monitoring of the UK and ice velocities in Iceland. Furthermore since 2000 we have conducted ESA and EC-FP7 funded projects to NERC funded research, data processing, interpretation and modelling, as well as calibration and validation of InSAR-derived DEMs and ground motion products.
Since the beginning of 2012, the EPOM and shallow geohazards and risks teams of BGS have been carrying out an internally funded NERC research project aimed at evaluating the potential of space-borne InSAR techniques to better understand landslide processes over Great Britain (ESA LPS 2013 abstract and IGARSS 2013 paper).
Feasibility of satellite SAR-based research and applications were first mapped over the entire landmass. This was based on the combined assessment, and modelling, of topographic and land cover effects. These were simulated using high resolution DEMs, land cover information from the EEA CORINE 2006 map and persistent scatterers (PS) datasets made available to BGS through the projects Terrafirma and PanGeo. The feasibility maps are being validated via ESA Category-1 project id.13543, and target sites affected by landsliding in Great Britain were identified as test sites for further validation and research with new InSAR methods to monitor urban and rural areas (e.g. Wales and southern England).
Ground motion studies are being carried out over these regions with ERS-1/2 and ENVISAT data covering the past 20 years, and analysis with InSAR techniques is helping improve our understanding of ground motion and land processes affecting these areas. Supporting landslide research is currently being carried out at BGS using both traditional mapping techniques and new technologies (see landslides at BGS).
BGS also has in-house SAR image processing capabilities with InSAR and multi-interferogram techniques, e.g. persistent scatterer interferometry (PSI) and small baseline subset (SBAS).
The BGS EPOM team is currently involved in joint research with the Nottingham Geospatial Institute (NGI) of the University of Nottingham, and is testing the capability of the newly developed intermittent SBAS (ISBAS) technique for monitoring ground motions in non-urban and rural areas of the UK, with various test sites in Wales and England, and a range of applications including landsliding, mining-related subsidence and uplift in UK coalfields, and peatland motions (EGU 2014 abstracts: COSMO-SkyMed, ISBAS North Wales, ISBAS peatlands and IGARSS 2013 paper).
These tests are supported by ESA Category-1 project ID 13543 on enhancement of landslide research and monitoring capability in Great Britain using C-band satellite SAR imagery and InSAR.
EPOM has won a grant from the German Space Agency (DLR) providing access to over 50GB of TerraSAR-X Radar data which we will use for the quantification of rapid ice-cap and glacier surface change and flow dynamics for the Breiðamerkurjökull and Virkisjökull glaciers in Iceland (TSX-Archive-2012 GEO1703 project). For more information on the Iceland Observatory please see BGS observatory at Virkisjökull, Iceland.
SAR processing studies are also being undertaken by EPOM over the archaeological and landscape heritage of the Nasca region (Peru) within the framework of the ESA Category-1 project ID 11073 in conjunction with researchers from the Department of Geography at Durham University and the Institute of Methodologies for Environmental Analysis and Institute for Archaeological and Monumental Heritage of the National Research Council of Italy. Two papers have been published in Archaeological Prospection; see references below.
European Volcano Observatory Space Services
GMES downstream to enable free access to geohazard information
GMES downstream for subsidence hazards in coastal lowland areas
ESA GMES pan-European ground motion hazard information service
Bateson, L, Cigna, F, Sowter, A, Boon, D. 2013. The application of the ISBAS InSAR method to the South Wales Coalfield. Joint Int. Symp. on Deformation Monitoring. Nottingham, UK, pp. 1–7.
Cigna, F, Bateson, L, Dashwood, C, Jordan, C, Sowter, A, Boon, D. 2013a. InSAR monitoring of landslides in Britain: BGS’ feasibility map and first ISBAS studies over the South Wales Coalfield. ESA Living Planet Symp., Edinburgh, UK, 9–13 Sept 2013, pp. 1–6.
Cigna, F, Bateson, L, Jordan, C, Dashwood, C. 2012. Feasibility of InSAR technologies for nationwide monitoring of geohazards in Great Britain. RSPSoc 2012, 12–14 Sept 2012.
Cigna F., Bateson L., Jordan C., Dashwood C. (2013b). Nationwide monitoring of geohazards in Great Britain with InSAR: feasibility mapping based on ERS-1/2 and ENVISAT imagery. IEEE Int. Geosci. & Remote Sensing Symp. (IGARSS), pp. 672-675.
Cigna, F, Tapete, D, Lasaponara, R, Masini, N. 2013c. Amplitude change detection with ENVISAT ASAR to image the cultural landscape of the Nasca region, Peru. Arch. Prosp., 20 (2), 117–131.
Tapete, D, Cigna, F, Masini, N, Lasaponara, R. 2013. Prospection and monitoring of the archaeological heritage of Nasca, Peru, with ENVISAT ASAR. Arch. Prosp., 20 (2), 133–147.
Contact Colm Jordan for more information.