Shear velocity structure beneath Northern Algeria from Rayleigh-wave analysis

Abstract

The few scientific studies of the crust and upper mantle in Northern Algeria are based mainly on regional Western Mediterranean studies. This area has a certain degree of deformation due to its location between the African and Eurasian tectonic plates. This study continues previous studies reporting possible traces of subduction zones or hot spots throughout the Mediterranean basin. After installing 17 permanent broadband seismic stations in this area, we used teleseismic events recorded between 2007 and 2016 to define the shear wave velocity (Vs) structure as a function of depth by inverting the Rayleigh wave group velocity dispersion curves using the single-station method. The group velocity measurements for periods of 5–200 s were selected through the inversion of the regionalized dispersion curve to compute average 1-D shear-velocity models at area around station, which helped generate the relative shear velocity variation (Δ Vid) maps at different depths for the study area. From the variation of Vs, we deduced Moho depth ranges of 20–50 km for the study area. From the Δ Vid maps, we noticed that for layers deeper than 60 km, the failed subduction slab traces could be observed in the eastern part. The central-western part appears to be congruent with the direction of convergence between the two tectonic plates. This finding is consistent with the results obtained from the GPS study.