## 1 Introduction  
Satellite interferometric synthetic aperture radar (InSAR) data have proven effective and valuable in the analysis of geohazards based on multi-temporal radar images and have played a key role in recent years representing a cost- and time-efficient support and/or alternative to geological and geotechnical investigations [1]. Starting from the end of the eighties and beginning of the nineties [2, 3], onward, the potential of satellite InSAR for cm or sub-cm level surface deformation mapping over a large area was revealed. Those works represented a milestone for the breakthrough of InSAR methods which proliferated during the following decades with a steady improvement and validation of several and different techniques (such as persistent scatterer interferometry--PSI, and small baseline subset--SBAS; [4]) through a large amount of scientific literature. This was especially thanks to international projects, such as Terrafirma [5], funded by the European Space Agency (ESA), and the EC-FP7 PanGeo project [6],and thanks to new SAR missions, such as ENVISAT in 2002, TerraSAR-X in 2007 and COSMO-SkyMed the following year. The proportional increase in the number of citations per year compared to the corresponding number of papers can be related to the increasing efforts in InSAR applications rather than the improvement or development of InSAR techniques (Figure 1). Italy is the only country worldwide where an InSAR database has been assembled successfully from the processing of \(\sim\)15,000 ERS and ENVISAT SAR scenes to cover an entire nation (>300,000 km\({}^{2}\)), and is now being extended with X-band COSMO-SkyMed data. The processing is part of a project funded by the Italian Ministry for the Environment, Territory and Sea in the framework of the Extraordinary Plan of Environmental Remote Sensing and essentially driven by the country's susceptibility to hydro-geomorphological risk [7]. In April 2014, with the launch of the first satellite of ESA's Sentinel-1 mission, Sentinel-1A [8], a new challenge has been set for InSAR applications: to provide, on a national scale, near real-time disaster monitoring, assessment, and response for geological processes [9]. In this paper, we aim to assess the feasibility of InSAR techniques to monitor the landmass of Great Britain to extend the work done by [10] who simulated SAR geometric distortions and predicted persistent scatterer densities for ERS and ENVISAT C-band SAR and InSAR applications in Great Britain. The target region encompasses an area of 243,610 km\({}^{2}\) made up of a main landmass and minor islands and islets. Since not all of the different geohazards affecting Great Britain produce ground displacement (e.g., flooding, storms, and wildfires), our assessment is limited to ground instability phenomena, such as natural compaction of recent river deposits [11] and loessic silt (largely confined to Southeast Essex and Northern Kent), shrink-swell terrains [12] found mainly in the southeast of the country, landsliding [13], land subsidence/uplift due to groundwater abstraction/recharge [14], glacial isostatic adjustment [15], dissolution of soluble rocks [16] principally in Cheshire, Pennines, and Wales, ground motions induced by human activities [17], and excavations and mine-water management in active and abandoned mining areas [18]. The United Kingdom is a country with limited direct experience of natural disasters and the British Geological Survey (BGS) archive confirms that just eleven people are known to have died as the results of British earthquakes since 1580 [19]. Moreover, despite an estimated 32,000 natural sinkholes, none has been responsible for a single death. Landslides are responsible of less than one death per year, apart from the Aberfan disaster of 1966 that claimed  
Figure 1: Number of articles, proceedings papers, and reviews found as of December 2016 in the ISI Web of Knowledge under the terms “InSAR” and “Interferometry” in the areas of remote sensing applied to Earth sciences; data from Thomson Reuters. over 144 victims [20].