European Ground Motion Service: production status and validation

The European Ground Motion Service (EGMS) allows a wide spectrum of users to access ground motion data over 30 European countries for free, under the Copernicus data policy. The EGMS aims to serve for various applications, of which geohazards are probably the primary target. Also, the Service establishes a baseline for studies dedicated to localised deformation affecting buildings and infrastructure in general.

The EGMS is the result of a massive computational effort to process thousands of Sentinel-1 images and derive three levels of products: (a) basic, i.e. line of sight (LOS) velocity maps in ascending and descending orbits referred to a local reference point; (b) calibrated, i.e. LOS velocity maps calibrated with a geodetic reference network and (c) ortho, i.e. components of motion (horizontal and vertical) anchored to the reference geodetic network. The EGMS is implemented under the responsibility of the European Environment Agency in the frame of the Copernicus Programme.

The EGMS baseline (2016-2020) and the first annual update (2016-2021) were made available to users in the summer of 2022 and in the first quarter of 2023, respectively. The EGMS products are displayed in the EGMS Explorer (https://egms.land.copernicus.eu/), where users can investigate the data in a 3D web interface, explore the temporal behaviour of ground motion through time series and download one or multiple data tiles. External web map services can be imported in the EGMS Explorer to ease the interpretation of the interferometric measurements.

The strategy to update satellite interferometric time series is a hot topic for wide area processing services. So that, one of the goals of this presentation is to show the EGMS update strategy, which should guarantee the best trade-off between the identification of new coherent targets and motion areas and the continuity of the Service in terms of technical implementation and noise level.

The expected wide usage of the EGMS products required to setup a validation system that has two goals: verify the usability of the data for the expected range of applications and assess the quality of the products with respect to service requirements. Validation is based on seven activities performed in sixteen different countries and in several validation sites, which are representative for thematic applications (e.g. mining-induced ground motion) in different environments of Europe. To guarantee reproducibility of results, the validation data (e.g. levelling or corner reflectors time series, landslide databases) will be made available to users according to licensing conditions. The results of the validation exercise will be available to users in Q3 2023.