Tectonic salient characterization based on GNSS data: The case of the Eastern Betic Tectonic Arc in the western Mediterranean

Abstract

Here we present the results of a geodetic analysis of several continuous and episodic stations located in SE Spain. Based on this analysis, we propose a new deformation field for the Eastern Betic Tectonic Arc, a tectonic salient related to an indentation process. This deformation field indicates that the velocity vectors exhibit a general NNW-SSE trend with respect to stable Eurasia. A detailed analysis reveals that, similarly to that occurring in other global indentation-dominated salients, the frontal part of the salient is accommodating most of this displacement. Also, active structures in the lateral limit of the indentation accommodate only a fraction of this movement. A detailed analysis reveals that shortening in the Eastern Betic Tectonic Arc is heterogeneous, as the fault deformation rate decreases southwards and eastwards. We calculate horizontal deformation rates for the Aguilas Arc, i.e., the southern faults of the Eastern Betic Tectonic Arc. According to our calculations, the Terreros Fault exhibits a left-lateral slip rate of 0.3 ± 0.1 mm/yr and the same horizontal shortening rate. The Lomo de Bas, Ramonete, and Moreras faults demonstrate a combined horizontal shortening rate of 0.4 ± 0.1 mm/yr, and nonsignificant strike-slip motion (0.0 ± 0.1 mm/yr). The Pe~nas Blancas Fault accommodates 0.6 ± 0.1 mm/yr of left-lateral displacement and 0.4 ± 0.1 mm/yr of cross-fault shortening. Finally, the Campo de Cartagena region experiences NNW-SSE shortening to a degree reaching 0.8 ± 0.1 mm/yr. In addition, we also discuss the general structural arrangement of the Eastern Betic Tectonic Arc while considering new geodetic data. We hypothesize that this arc is compatible with an asymmetric indenter, with limited lateral extension towards the west. Our detailed kinematic and geometric analyses indicate an N340◦E indentation direction.