Surface Velocities and Strain-Rates in the Euro-Mediterranean Region From Massive GPS Data Processing

Abstract

In this work we present and discuss new geodetic velocity and strain-rate fields for the Euro-Mediterranean region obtained from the analysis of continuous GNSS stations. We describe the procedures and methods adopted to analyze raw GPS observations from >4000 stations operating in the Euro-Mediterranean, Eurasian and African regions. The goal of this massive analysis is the monitoring of Earth’s crust deformation in response to tectonic processes, including plate- and micro-plate kinematics, geodynamics, active tectonics, earthquake-cycle, but also the study of a wide range of geophysical processes, natural and anthropogenic subsidence, sea-level changes, and hydrology. We describe the computational infrastructure, the methods and procedures adopted to obtain a three-dimensional GPS velocity field, which is used to obtain spatial velocity gradients and horizontal strain-rates. We then focus on the Euro-Mediterranean region, where we discuss the horizontal and vertical velocities, and spatial velocity gradients, obtained from stations that have time-series lengths longer than 6 and 7 years, which are found to be the minimum spans to provide stable and reliable velocity estimates in the horizontal and vertical components, respectively. We compute the horizontal strain-rate field and discuss deformation patterns and kinematics along the major seismogenic belts of the Nubia-Eurasia plate boundary zone in the Mediterranean region. The distribution and density of continuous GNSS stations in our geodetic solution allow us to estimate the strain-rate field at a spatial scale of ∼27 km over a large part of southern Europe, with the exclusion of the Dinaric mountains and Balkans.

A submarine morphotectonic analysis combining GIS-based methods and virtual reality: Case study of the low-rate active thrust faulting off Boumerdès (Algeria)

“…Among the rare examples of reactivated passive margins, the Algerian margin case study has received a peculiar attention in the last 20 years. Indeed, this margin illustrates a typical case of a weak mantle lithosphere with short length-scales of deformation (Hamai et al, 2015;Auzemery et al, 2021) and locates at a diffuse plate boundary which absorbs most of the slow convergence between Africa and Europe (Palano et al, 2015;Bougrine et al, 2019;Serpelloni et al, 2022;Billi et al, 2023), producing rare but strong, sometimes damaging earthquakes (Hamdache et al, 2010;Bellalem et al, 2022). The 1856The , 1954The , 1980The and 1985 earthquakes (Figure 1) are among the main historical and instrumental earthquakes worth to mention.…”

Active tectonics of the Circum-Pannonian region in the light of updated GNSS network data

“…This broad region of subsidence includes the Circum-Pannonian region (Marotta et al 2004;Caron et al 2018;Vishwakarma et al 2022), and is estimated to be < 1 mm/yr. Hammond et al (2021), Serpelloni et al (2022) as well as Valdés et al (2022) estimate a similar pattern and magnitude of subsidence from interpolated GNSS data, if we disregard a number of smaller regions of uplift that may be affected by mantle upwelling or isostatic adjustment. If this large-scale subsidence is indeed a response to deglaciation, it is a periodical phenomenon on the time scale below that of the Quaternary, meaning that relative vertical motions capture the average Quaternary displacements better than the currently observed absolute vertical motions.…”

“…A more suitable base for comparison is provided by recent studies of Piña-Valdés et al ( 2022) and Serpelloni et al (2022). These studies incorporate GNSS data at a larger scale and while they include the Pannonian region their focus is on larger areas; the former is a Europe-wide study, while latter is focusing on the Mediterranean region.…”

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

“…We analyze the raw GPS observations using the GAMIT/GLOBK (version 10.71) software (Herring et al, 2018), following the standard procedures of the repro2 IGS reprocessing scheme (http://acc.igs.org/reprocess2.html, last access: 1 September 2021). This is part of a large processing effort, including > 4000 stations in the Euro-Mediterranean and African regions (Serpelloni et al, 2022), where sub-networks, made up of < 50 stations dynamically and optimally selected based on daily data availability, are processed independently with GAMIT and later tied together using common sub-net tie sites and IGb14 core stations using the GLOBK software. The details of the processing are given in Sect.…”