Geodetic evidence of anomalous WSW displacement and salt tectonic evolution of the Essaouira Onshore, Atlantic High Atlas (Morocco)

The Geodetic observations derived from eight years (2010-2018) of the Essaouira continuous GPS station have revealed a WSW horizontal displacement of 3mm/year and an active uplift of 1mm/year relative to the Nubian Plate, which characterizes this basin than the other Moroccan coastal region. Even if this basin's vertical movements (subsidence) have been geologically described, the GPS data analysis method made it possible to calculate the vertical movement velocity with high accuracy. At the same time, the horizontal movement has never been described in the literature. Combining geophysical and geological data allows us to identify and explain the main probable factors behind these abnormal movements. Even this movement may result from the reactivation of pre-existing faults as part of the post-breakup evolution of the Atlantic passive margin, or it could be the result of a local process such as salt tectonics.

Keywords; GPS, Atlantic margin, Essaouira, uplift, WSW displacement, Salt tectonics