Topo-Iberia CGPS network: A new 3D crustal velocity field in the Iberian Peninsula and Morocco based on eleven years (2008–2019)

Abstract

The Topo-Iberia network covering the Spanish part of the Iberian Peninsula and Morocco was established in 2008. Following the first publication of the horizontal velocity field based on an analysis of the first four years (2008–2012) in 2015, a new 3D velocity field based on eleven years (2008–2019) is presented. The double-differencing technique is applied with GAMIT software, and the precise point positioning (PPP) technique is applied with GipsyX software for GPS processing to obtain loosely constrained solutions. Then, a Kalman filter is used to merge both solutions using GLOBK software and produce a velocity solution. The combined velocity solution is presented as a new horizontal velocity field and the first vertical velocity field of the Topo-IberiaCGPS network. A global viewof the data quality from the Topo-Iberia stations is also presented for the first time, as well as a program specifically created to convert GipsyX gdcov files to SINEX files, gdcov2sinex.sh. The results are in good agreement with previous publications, except in the Betic Cordillera, where the new velocities with respect to Eurasia are generally lower and present a higher southwestward component rather than a purely westward motion. The main discrepancy is observed at the ALJI station, where the maximum velocity is reached (3 ± 0.1 mm/yr), showing west‒northwestward motion. The smallest and highest residual displacements with respect to Eurasiaoccur in northern Iberia and Morocco, respectively. The results support the conclusions of other studies that a clockwise block rotation occurs at present in the northern branch of the Gibraltar Arc. The velocities indicate a northwest‒southeast convergence rate of 3.5 ± 0.1 mm/yr with respect to Nubia. A general low subsidence (mean value of 0.5 ± 0.1 mm/yr) is observed in the Iberian Peninsula except for some isolated stations presenting uplift.

Quality assessment of the Topo-Iberia CGPS stations and data quality's effects on postfit ionosphere-free phase residuals

“…Since this indicator is not explicitly stated among the recommendations of the IGS [16], it has been considered only in the thresholds RF1 and RF2. Regarding the study of the relationship between the data quality and the LC phase residuals, the postfit RMS scatter of phase residuals for each station have been extracted from the daily GAMIT's output file autcln.post.sum, and from the GipsyX's output file Summary obtained in the GPS processing by García-Armenteros [5]. Finally, the possible relationship between these results and those from the analyses based on statistics of the quality indicators has been studied.…”

“…García-Armenteros [5] provided a new 3D crustal velocity field in the Iberian Peninsula and Morocco based on eleven years (2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019). The GNSS data processing software used was GAMIT version 10.71 [10] applying doubledifferencing technique, and GipsyX version 1.7 [11] applying PPP technique.…”

“…The periods with incomplete or missing files, or poor quality, are easily identified. This quality check was taken into account in the processing of the Topo-Iberia network by García-Armenteros [5]. When the data were selected for processing, the effect of the periodical signals in the estimation of velocities established by Blewitt and Lavallée [21] was considered selecting data spans of integer-plushalf years and longer than 4.5 years, so that the affectation was the least possible.…”

Antenna environment's effects on elevation angle dependent ionosphere-free phase residuals, and geodetic monument noise in the Topo-Iberia CGPS network

“…The original equipment consisted of Trimble NetRS dual-frequency receivers and Trimble GNSS Choke-Ring antennas, with SCIGN radomes where environmental conditions so recommended. The last GPS processing of the Topo-Iberia network was carried out by García-Armenteros (2023a) providing a new 3D crustal velocity field in the Iberian Peninsula and Morocco based on 11 years (2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019). The GNSS processing software used was GAMIT version 10.71 (Herring et al 2018) and GipsyX version 1.7 (Bertiger et al 2020).…”

“…4-char ID, geographic position, installation/dismantling date (Year-Day Of Year), geodetic monument type, and institution in charge on control date 2020-02-11. The geographic positions are taken fromGarcía-Armenteros (2023a)…”