3D GNSS Velocity Field sheds light on the Deformation Mechanisms in Europe: effects of the vertical crustal motion on the distribution of seismicity

Crustal deformation and seismicity in Europe are still poorly understood. Seismic activity is classically ascribed to crustal strain rates generated by tectonic deformation. However, crustal deformation is not only due to tectonic loading, but can also be related to isostatic and buoyancy processes that induce additional strains on the crust by flexure. The influence that those processes have on seismic activity, as well their interaction, is still controversial, and the main limitation to study it is because the deformation processes are commonly analyzed separately in small regions. We present here a 3D secular velocity field that covers Eurasia and its plate boundaries including 4508 GNSS stations obtained by combining 10 different datasets. We have developed a method based on spatial filtering to identify outliers and smooth the velocity field, and have computed a strain rate map representative of the main deformation processes that affect Europe. The vertical and horizontal deformation features were compared with earthquake recurrence models obtained from the spatial and temporal distribution of the seismicity in Europe. Our results suggest that is not possible to explain the seismicity of Europe based on the horizontal strain rate maps only. In some areas markers of the crustal flexure such as the vertical velocity field and its derivative, may help to interpret earthquake distribution models derived from geodetic data.