During the 1980s, sinkholes began to develop along the Dead Sea shores, and the phenomenon has been increasing over the years. Its creation is attributed to the dissolution of a subsurface salt layer (the ‘Sinkholes Salt’) by fresh groundwater that comes into contact with the salt layer due to the continuous drop of the Dead Sea water level and the eastward migration of the fresh-saline water interface.
The formation of sinkholes in the area poses a risk to both existing and planned infrastructure and recreational activities. Since the formation of sinkholes is directly affected by the presence of the ‘Sinkholes Salt’ layer, information about its location, depth, and thickness is essential to understand how to mitigate the sinkhole hazard in the area.
In this study, we delineated the ‘Sinkhole Salt’ layer using the Time Domain Electromagnetics method (TDEM), which is a non-invasive geophysical technique. The ‘Sinkholes Salt’ layer was identified by a high resistivity anomaly (around 1 Ohm-m) compared to the enveloping layers, which are saturated by the Dead Sea brine and have lower resistivity. This contrast makes it a good and reliable target for the TDEM method.
The lateral and horizontal extension of the ‘Sinkholes Salt’ layer was clearly defined in a cross-section of TDEM measurements from the Dead Sea shores to the west. Our measurements agree well with observation boreholes and one field exposure from the Ze'elim fan, confirming their validity. Since these measurements are simple to acquire and inexpensive (compared to boreholes), it is suggested to examine the use of this method in additional locations around the lake.