Overview of the geophysical studies in the Dead Sea coastal area related to evaporite karst and recent sinkhole development

Abstract

Abstract:Since the early 80s, a progressively increasing number of sinkholes appeared along the Dead Sea coastal line. It has been found that their appearance is strongly correlating with the lowering of the Dead Sea level taking place with the rate of approximately 1 m/yr. Location of areas affected by sinkhole development corresponds to location of the salt formation deposited during the latest Pleistocene, when the Lake Lisan receded to later become the Dead Sea. Water flowing to the Dead Sea from adjacent and underlying aquifers dissolves salt and creates caverns that cause ground subsidence and consequent formation of sinkholes. Before subsidence, these caverns are not visible on the surface but can be investigated with surface geophysical methods. For that, we applied Surface Nuclear Magnetic Resonance (SNMR), Transient Electromagnetic (TEM) Seismic refraction and reflection, Multichannel Analysis of Surface waves (MASW), microgravity and magnetic surveys and their combinations. Our geophysical results allowed us to locate the salt formation and to detect caverns in salt thus contributing to better understanding sinkhole development mechanisms. Comparison of sinkhole appearance along the western DS shore derived from the recent database (2017) shows that predictions made on the base of geophysical data (2005)(2006)(2007)(2008) are now confirmed thus demonstrating efficiency of our study. In this paper, we briefly present a summary of up to date knowledge of the geology and hydrogeology of Dead Sea basin, of the physical properties of the salt rock and the most popular models explaining mechanisms of sinkhole development. We also share our experience gained during geophysical studies carried out in the framework of national and international research projects in this area for the last 20 years.Dead Sea, evaporate karst, geophysics, sinkholes Ezersky M.G., Legchenko A., Eppelbaum L. and Al-Zoubi A., 2017. Overview of the geophysical studies in the Dead Sea coastal area related to evaporite karst and recent sinkhole development.

Geomechanical modelling of sinkhole development using distinct elements: model verification for a single void space and application to the Dead Sea area

“…This approach is possibly suitable for assessing the factor of safety of an individual, fully developed cave and for deriving a relation between measured surface subsidence and cavern configuration. However, the geometries of voids involved in sinkhole development are often non-singular, irregular and distributed on lots of scales (Abelson et al, 2017;Al-Halbouni et al, 2017;Ezersky et al, 2017;Gutiérrez et al, 2016;Parise et al, 2018;Yizhaq et al, 2017). Alternatively, continuum-based corrosion models have addressed the rock dissolution and void growth in a hydrogeological framework (Kaufmann and Romanov, 2016;Shalev and Lyakhovsky, 2012).…”

“…Here, we consider geotechnical parameters for the three main material types involved in sinkhole formation at the Dead Sea region: (1) la-custrine clayey carbonates and evaporites, (2) alluvial sands and gravels and (3) pure rock salt (halite) ( Table 2). For lacustrine mud, friction angle, cohesion, porosity and density parameters from laboratory tests are used (Ezersky et al, , 2017Frydman et al, 2008Frydman et al, , 2014. For the alluvial sediments, upper limits are given by nearby field investigations in firm sandstone rocks (El-Naqa, 2001) and also by published values for medium-grained Quaternary sand-gravel (Carter, 1983;Manger, 1963;Taqieddin et al, 2000).…”

Application of ground penetrating radar in karst environments: An overview

“…Poleg hitrej-šega raztapljanja so takšne kamnine tudi mehansko manj odporne in stabilne ter bolj duktilnega značaja. Georadarsko metodo so uporabili v številnih raziskavah vzdolž Mrtvega morja (Frumkin et al, 2011;Ezersky et al, 2017;Ronen et al, 2019). V zadnjih 30 letih je bilo evidentiranih na stotine udorov vzdolž Mrtvega morja tako v Izraelu kot v Jordaniji, pri čemer je prišlo do več nesreč na urbanih območjih (Frumkin et al, 2011).…”

Answers to interactive comments Rev. 1

“…Estimated geomechanical properties of main materials in sinkhole-affected areas at the Dead Sea. References: Ezersky et al (2017); Ezersky and Livne, (2013);Frydman et al (2008Frydman et al ( , 2014; Hoek (2007); Khoury (2002); Manger (1963); Polom et al (2018); Zhu (2010 the friction angle. We use a friction angle of φ = 54 • , depth z = 20-40 m and an intercept of n = 259 kPa for a specific rock weight of 18 kN m −3 (Frydman et al, 2014).…”