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GMES Terrafirma: InSAR comes of age

Ren Capes(1) and Geraint Cooksley(1)

(1) NPA, Crockham Park, Kent TN8 6SR, United Kingdom


Terrafirma is one of ten Service Element projects being run by the European Space Agency under the Global Monitoring for Environment and Security initiative. The project is establishing a pan-European ground motion hazard information service in support of policies aimed at protecting the citizen. ‘Ground motion hazards’ include subsidence in all its forms, landslides and the effects of seismicity, though initially, and to be immediately operational, the focus is on urban subsidence. The service is to be delivered to end-users primarily by National Geological Surveys. The project initiator, Prime and Co- ordinator is NPA Satellite Mapping of UK.

The technology at the base of such a large-scale undertaking uses the data collected by European radar satellites in a process called Synthetic Aperture Radar Interferometry, or InSAR for short. InSAR can cover whole cities and regions, and because an archive exists of ‘repeat’ satellite data, measurements can uniquely be provided back in time for the last twelve years. Enhanced products are being offered by the Geological Surveys who are integrating pre-existing and possibly in situ data with InSAR results to provide ‘causal’ and ‘modelled’ information services.

With the initial focus on urban subsidence, 186 European towns representing 26% of the total population have been identified for InSAR processing. Only 18 have so far been completed, though Stage 2 of the project (2-5 years) is anticipated as funding the remaining processing.

In the first 20-month Stage of Terrafirma the emphasis is on consolidating pan-European supply and demand. Under NPA’s lead, the project started with two InSAR providers, NPA of UK and TRE of Italy, but now includes all four acknowledged European providers with the addition of Gamma Remote Sensing of Switzerland and Altamira Information of Spain - the first time that Europe’s normally competitive InSAR providers have collaborated together in one project.

The project started in early 2003 with a core of National Geological Surveys including the UK, France and the Netherlands, but has now expanded with the addition of Norway, Poland, Israel, Ireland and Greece, and negotiations are underway with Spain, Germany, Japan and Russia. Complete coverage by National Geological Surveys, at least for Europe, is planned. Civil engineers are significant end-users of ground motion information, and they are represented within Terrafirma by Arup of UK and Enel Hydro of Italy. The project remains open to the participation of other major civil engineering organisations.

Terrafirma includes three ‘expert consultants’ – AETS of France who are examining the cost-benefits of the service, the British Institute of International and Comparative Law who are detailing the policy areas supported by the activity, and SciSys of the UK who are specifying the system architecture required for a standardised European service. Finally, the project includes three high profile ‘Strategy Group’ members from Italy, Germany and Poland whose role it is to review and endorse all project output.

For more information about the Terrafirma project or the Global Monitoring for Environment and Security initiative in general please contact or visit


Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry