Geopositioning time series from offshore platforms in the Adriatic Sea

Abstract

We provide a dataset of 3D coordinate time series of 37 continuous GNSS stations installed for stability monitoring purposes on onshore and offshore industrial settlements along a NW-SE-oriented and ~100-km-wide belt encompassing the eastern Italian coast and the Adriatic Sea. The dataset results from the analysis performed by using different geodetic software (Bernese, GAMIT/GLOBK and GIPSY) and consists of six raw position time series solutions, referred to IGb08 and IGS14 reference frames. Time series analyses and comparisons evidence that the different solutions are consistent between them, despite the use of different software, models, strategy processing and frame realizations. We observe that the offshore stations are subject to significant seasonal oscillations probably due to seasonal environmental loads, seasonal temperature-induced platform deformation and hydrostatic pressure variations. Many stations are characterized by non-linear time series, suggesting a complex interplay between regional (long-term tectonic stress) and local sources of deformation (e.g. reservoirs depletion, sediment compaction). Computed raw time series, logs files, phasor diagrams and time series comparison plots are distributed via PANGAEA ( https://www.pangaea.de ).

Fig. 1

(a) Map distribution of the continuous GNSS stations provided by Eni S.p.A. Legend: 1) GNSS stations installed on storage and treatment centers, 2) GNSS stations installed on offshore platforms, 3) continuous GNSS stations developed and managed by different local, national and international Institutions and Agencies (INGV, ASI, ITALPOS, NETGEO, etc), 4) Oil/Gas prospection and production concession. (b) Temporal raw data availability of the GNSS dataset (see Table 1 for additional details).

Fig. 2

Frequency histograms of WRMS values for the North, East and Up components of filtered residual time series.

Fig. 3

Example of phasor diagrams of annual (top) and semiannual (bottom) signals for station AGOB (see Table 1). Amplitudes of the estimated sine and cosine parameters (see Eq. (1)) are plotted for the North, East and Up components. The upper-right plot represents the key to correlate the maxima phase direction with the day year period. Phases are referred to January 1 and time increases clockwise.

Fig. 4

Example of time series comparison from the different solution described in the main text. Each time series is reported after correcting offsets and removing the linear trend as defined in Eq. (1).

Fig. 5

Frequency histograms of residual values between computed linear trend values with respect to the mean values (Table 5).

Fig. 6

Horizontal velocity field comparisons. Velocities are referred to a Eurasian reference frame. Lower inset: zoom on Calabria region; upper inset: zoom on the Northern Adriatic region.

Fig. 7

(a) mean vertical velocity field 5; (b) comparison of the residual vertical velocity values for all the analyzed solutions.