Study of the salt layer environments using TEM method in the Dead Sea sinkhole problem

A new geophysical methodology for sinkhole hazard assessment is under development. The key point of the new methodology is delineating salt distribution, in particular the salt edge, based on the time electromagnetic method analysis. We consider a new approach to use the Transient Electromagnetic (TEM) method in its FAST modification for studying the distribution of bulk resistivity in the vicinity of the salt edge and salt layer properties: porosity, depth and thickness. This methodology is based on separate resistivity mapping of the subsurface east and west of salt layer edge that was revealed by seismic refraction method. Then we can separate the investigation area into two"sub-areas": (1) "salt" area, where the measured resistivity is influenced by the salt porosity (estimated from the Archie's law); (2) "no-salt" area, where the measured resistivity is influenced by the groundwater salinity estimated using the resistivity-salinity inter-relations obtained for the Dead Sea region. West of the salt edge resistivity of aquifer associated with the aquifer salinity is mapped, whereas east of that salt layer resistivity related to its porosity is mapped. In Jordan it works reversely.