Recent Euler pole parameters and relative velocities of the Nubia–Eurasia and Nubia–South America plates estimated using GPS technique

Abstract

The convergence of the Nubian plate toward Eurasia and the spreading rate between the Nubian and South American plates are currently subjects of scientific debates. In this paper, we improve the estimation of Euler pole parameters and the recent relative velocities of the Nubian plate using Global Positioning System (GPS) velocities. These estimates are based on mathematical models and statistical tests for plate tectonic motion represented on a spherical surface. First, we derive the angular velocity and the precise coordinates of the Euler pole to describe the Nubian plate absolute motion expressed in the ITRF2014 geodetic system. This derivation is obtained by inverting the horizontal velocities of 202 GPS stations well distributed across the Nubian plate. Then, we use the same data to obtain the current relative velocities and parameters of the Euler pole characterizing the Nubia–Eurasia and Nubia–South America relative plate motion. A number of 21 and 29 GPS stations located on tectonically stable domains are used to fix the Eurasian and the South American plates, respectively. The results show Nubia–Eurasia relative velocities ranging from 1 to 7 mm/yr, with a direction of NW to WNW for the northern Nubian plate. The velocity in the southern part of this plate reveals a NNE to N direction. The inversion of these velocities allows the determination of the Euler pole parameters: the coordinates PNub-Eu(λNub-Eu=-23.17∘±0.92892;φNub-Eu=-5.62∘±0.72322) and the angular velocity ΩNub-Eu=0.053∘/Myr±0.00101. On the other hand, the estimated relative velocity of Nubia–South America is varying in the range of 15–30 mm/yr, with a NE to ENE direction and rotating around the pole PNub-SA(λNub-SA=-44.5263∘±0.57624,φNub-SA=66.7484∘±0.16524) with an angular velocity (Ω Nub - SA= 0. 26689 ∘/ Myr ± 0.0007). The obtained research results demonstrate an improved precision compared to the existing studies. Furthermore, the use of the Algerian GPS velocities played a key role in the enhancement of the estimates’ precision, which allows us to better understand and monitor the crustal deformations at the limit of the plates