17 Nov 2021
17 Nov 2021
Status: this preprint is currently under review for the journal SE.

Common mode signals and vertical velocities in the great Alpine area from GNSS data

Francesco Pintori1, Enrico Serpelloni1,2, and Adriano Gualandi1 Francesco Pintori et al.
  • 1Istituto Nazionale di Geofisica e Vulcanologia (INGV), Osservatorio Nazionale Terremoti, Roma, 00143, Italy
  • 2Istituto Nazionale di Geofisica e Vulcanologia (INGV), Bologna, 40128, Italy

Abstract. We study time series of vertical ground displacements from continuous GNSS stations to investigate the spatial and temporal contribution of different geophysical processes to the time-varying displacements that are superimposed on vertical linear trends across the European Alps. We apply a multivariate statistics-based blind source separation algorithm to both GNSS displacement time series and to ground displacements associated with atmospheric and hydrological loading processes, as obtained from global reanalysis models. This allows us to associate each retrieved geodetic vertical deformation signal with a corresponding forcing process. Atmospheric loading is the most important one, reaching amplitudes larger than 2 cm. Besides atmospheric loading, seasonal displacements with amplitudes of about 1 cm are associated with temperature-related processes and with hydrological loading. We find that both temperature and hydrological loading cause peculiar spatial features of GNSS ground displacements. For example, temperature-related seasonal displacements show different behaviour at sites in the plains and in the mountains. Atmospheric and hydrological loading, besides the first-order spatially uniform feature, are associated also with NS and EW displacement gradients.

We filter out signals associated with non-tectonic deformation from the raw time series to study their impact on both the estimated noise and linear rates in the vertical direction. While the impact on rates appears rather limited, given also the long-time span of the time-series considered in this work, the uncertainties estimated from filtered time-series assuming a power law + white noise model are significantly reduced, with an important increase in white noise contributions to the total noise budget. Finally, we present the filtered velocity field and show how vertical ground velocities are positively correlated with topographic features of the Alps.

Francesco Pintori et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on se-2021-136', Anonymous Referee #1, 04 Jan 2022
  • RC2: 'Comment on se-2021-136', Anonymous Referee #2, 09 Feb 2022
  • RC3: 'Comment on se-2021-136', Anonymous Referee #3, 09 May 2022

Francesco Pintori et al.

Francesco Pintori et al.


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Short summary
We study time varying vertical deformation signals in the European Alps by analyzing GNSS position time series. We associate each deformation signal to geophysical forcing processes, finding that atmospheric and hydrological loading are by far the most important cause of seasonal displacements, together with temperature-related processes. Recognizing and filtering out non-tectonic signals allows us to improve the accuracy and precision of the vertical velocities.