Tracking tectonic strain changes over time using InSAR, GNSS, and trajectory models

It is well established that we can estimate the spatially continuous 3D velocity field of the Earth’s surface by combining InSAR and GNSS. One notable example is the VELMAP¹ approach which solves for the surface 3D motions in addition to reference frame alignment parameters and topography-correlated atmospheric noise. With this 3D surface velocity model, it is then a trivial step to convert to a strain map containing the spatial details of tectonic processes. One key challenge for our community is to extend such strain analysis as a function of time. This is because we know that tectonic velocities change significantly over human observable timescales, especially after moderate to large earthquakes and sometimes during interseismic periods.

In this EGU 2026 contribution, I will be showing the progress made in characterizing continental surface strain as a function of time by applying trajectory models² and a variation of the VELMAP approach to time series of InSAR displacements and GNSS coordinates. InSAR displacements come from the multi-interferogram time series processing of the European Ground Motion Service³, while the GNSS coordinates come from the European Plate Observing System GNSS community (EPOS-GNSS⁴).

 

References:

[1] Wang, H. and Wright, T.J., 2012. Satellite geodetic imaging reveals internal deformation of western Tibet. Geophysical Research Letters, 39(7).

[2] Bedford, J. and Bevis, M., 2018. Greedy automatic signal decomposition and its application to daily GPS time series. Journal of Geophysical Research: Solid Earth, 123(8), pp.6992-7003.  [https://github.com/TectonicGeodesy-RUB/Gratsid]

[3] European Ground Motion Service: Basic 2019-2023 (vector), Europe, yearly. European Union's Copernicus Land Monitoring Service information, https://land.copernicus.eu/en/products/european-ground-motion-service/egms-basic (Accessed on 15.01.2026). DOI: doi 10.2909/7eb207d6-0a62-4280-b1ca-f4ad1d9f91c3

[4] Fernandes, R., Bruyninx, C., Crocker, P., Menut, J.L., Socquet, A., Vergnolle, M., Avallone, A., Bos, M., Bruni, S., Cardoso, R. and Carvalho, L., 2022. A new European service to share GNSS Data and Products. Annals of Geophysics, 65(3), p.DM317.