Estimating the ages of fault scarps in the Arava, Israel

Abstract Systematic age estimations for the numerous fault scarps that rupture the alluvial fans in the southern Arava valley, Israel, are rare or nonexistent. Here we estimate the morphologic ages of several of these faults by the fault scarp degradation method and show that the ages agree well with ages estimated by the independent, earlier soil-geomorphic studies. The values we use for the coefficient of diffusion for the fault scarp degradation process are calibrated by a few numerical ages. These ages were determined by the Infrared Stimulated Luminescence (IRSL) method on one of the fault scarps and are the only numerical ages in the region. The morphologic ages are all in a correct stratigraphic order and in agreement with field stratigraphic relationships determined by earlier studies. They indicate that the studied fault scarps range in age from the latest Pleistocene to very recent times. The most recent fault scarps, which were analyzed are less than 2000 years old and perhaps much younger. They indicate that at least two earthquakes with magnitude > 6.5 have affected southern Israel and Jordan during that period. It is emphasized that so far we have studied only a limited number of fault scarps and therefore the number of large earthquakes during the last one to two millennia is a minimum.