How Much Nubia‐Eurasia Convergence Is Accommodated by the NE End of the Eastern Betic Shear Zone (SE Spain)? Constraints From GPS Velocities

Abstract

We present the first GPS‐derived geodetic observations from the NE end of the Eastern Betic Shear Zone obtained from the Bajo Segura GPS network (SE Spain). The network has 11 GPS sites and was sampled four times between 1999 and 2013. Despite the low signal‐to‐noise ratio of the residual velocities obtained, the velocities are nonzero at 95% confidence level. We postulate that the GPS data point to the partitioning of deformation into the NNW–SSE shortening and a N70E left‐lateral component. The maximum deformation rates are located along the two main active faults in the study area. The maximum shortening rates (north component) in the southern region of the Bajo Segura Basin vary from west to east, ranging from 0.2 to 0.7 mm/year along the Bajo Segura Fault Zone. On the northern border of the basin, along the Crevillente Fault Zone, left‐lateral displacement varies between 0.4 and 0.7 mm/year in the E‐W direction. The GPS‐based regional geodynamic models of the Western Mediterranean indicate that the residual shortening of the Eurasia‐Nubia plate convergence is accommodated in the eastern part of the Iberian Peninsula and the Algero‐Balearic Basin. Our results indicate that part of this residual deformation occurs at the NE end of the Eastern Betic Shear Zone, but significant deformation must be accommodated also to the north (External Betics) and to the south (Cartagena Basin and offshore area). We postulate that Eurasia‐Nubia plate convergence is transferred to the Eastern Betics because of the thin and rigid (potentially oceanic) crust of the Algero‐Balearic Basin, which acts as an indenter.

Modelling earthquake rupture rates in fault systems for seismic hazard assessment: The Eastern Betics Shear Zone

“…Although some authors (e.g. Alfaro et al, 2012a) suggest that the deformation associated to the BSF decreases towards the E, from a conservative perspective we assigned the same slip rate range as for BSF-3 (0.12-0.3 mm•yr −1 ), which is consistent with new GPS results in that sector (Borque et al, 2019). -AMF-3: There are no slip rate estimations for this section.…”

Fault System-Based Probabilistic Seismic Hazard Assessment of a Moderate Seismicity Region: The Eastern Betics Shear Zone (SE Spain)

“…Similarly, geodetic velocities of CF are in agreement with its geological slip rates (1.3 ± 0.2 mm/yr; Echeverria et al, 2015). In the NE end of the EBSZ GPS data indicates a partitioning of the deformation into lateral and reverse components, and compatibility with the kinematics of CAF and BSF, respectively (Borque et al, 2019).…”

Lateral variations of pressure-temperature evolution in non-cylindrical orogens and 3-D subduction dynamics: the Betic-Rif Cordillera example

“…Then, after ∼8 Ma, extension was replaced by a dominant N-S contractional regime. This recent N-S compression led to modest finite shortening rates of a few mm/yr (Borque et al, 2019;Valetti et al, 2019) and has thus not strongly modified the crustal thickness, preserving the main extensional contacts in the internal zones of the Betics and the Rif. The Internal Zones were then affected by E-W directed very large-scale folds associated with the relieves of Sierra Los Filabres, Sierra Nevada or Sierra Contraviesa (Fig.…”