Is the Jericho escarpment a tectonic or a geomorphological feature? Active faulting and paleoseismic trenching

The Jericho fault is considered to be the main active fault in the northern Dead Sea-lower Jordan Valley. In previous studies it has been identified by a prominent linear topographic escarpment that is thought to be the surface expression of this fault on land north of the Dead Sea. In this study, the paleoseismic natures of the escarpment and the fault were examined. Seismic activity was investigated in a series of three trenches excavated south of the fault trace on the surface. These trenches show evidence for Late Holocene faulting. A fourth trench excavated 300 m farther to the south exposed continuous, finely laminated marl from the-80-ka Samra Formation at a depth of 2-0.6 m below the surface, with no evidence of faulting. This could suggest that the fault on land is segmented and that the nature of its activity changes from north to south toward the lake. Indeed, the continuation of this fault under the waters of the Dead Sea reveals active faulting along a sharp, segmented, linear bathymetric break, where the steep margin slope on the west meets the flat lake bottom. Evidence of drastic climatic changes and erosion are present in all trenches that were excavated, indicating that the prominent escarpment may in part be an erosional feature, perhaps formed by incision of an ancient Jordan River or along a Holocene lakeshore. A channel fill of a lacustrine nature that followed a period of erosion is interpreted as a high stand of the Dead Sea, which is contemporaneous with the Younger Dryas cooling period.