Comment on "Active coastal thrusting and folding, and uplift rate of the Sahel Anticline and Zemmouri earthquake area (Tell Atlas, Algeria)", by S. Maouche, M. Meghraoui, C. Morhange, S. Belabbes, Y. Bouhadad, H. Haddoum. [Tectonophysics, 2011, 509, 69-80]
Résumé
Based on geomorphologic analyses and leveling survey of Quaternary coastal indicators (i.e. marine terraces and notches) along of a 50-km-long coastal stretch of the Algerian coast west of Algiers, Maouche et al. (2011) interpret the coastal segment to have undergone high uplift rates, i.e. 0.84-1.19 mm/yr since last interglacial maximum (MIS 5e, 122±6 ka in Table 1, ~140 ka in Maouche et al., 2011) and ~2.5 mm/yr for the last 31 ka. This uplift was said to be due to repeated seismic events that would have occurred during the last ~140 ka, and more particularly during the late Pleistocene. We raise major issues about the interpretation proposed by Maouche et al. (2011). These issues deal with 1) the use of previous chronological data and the chronostratigraphy proposed, 2) processes involved in the creation of coastal staircase morphology on the coast west of Algiers, 3) anomalously high uplift rates compared to other available data on the same geomorphic features (marine terraces) in the same setting of reactivated passive margins, and 4) the fold geometry used for modeling of fold growth and its implications for coseismic surface deformation and uplift estimates. In other words, we contest the statements that coseismic deformation is the cause of staircase morphology on the Mediterranean coast west of Algiers and that very large (M>7) earthquakes have occurred there in the past.