Najib Abou Karaki

Space-borne radar interferometric mapping of precursory deformations of a dyke collapse, Dead Sea area, Jordan

Satellite radar interferometry provides a technique to monitor a zone involving active salt tectonic phenomena. We detected movements in the Dead Sea area between 1993 and 1999. These preceded the catastrophic collapse (22 March 2000) of a newly built 12 km dyke belonging to the industrial salt evaporation ponds of the Arab Potash Company. Eighteen other dykes are present and still operational in this area of complex seismotectonic and hydrogeological settings. We used differential Synthetic Aperture Radar (SAR) interferometry (DInSAR) to investigate precursory deformations. Analysis of data shows that the collapsed area and its surroundings were in active subsidence at least 7 years before the event (maximum 44 mm in slant range from 16 December 1995 to 11 October 1997). This case emphasizes DInSAR as a tool suitable to identify deformations in such sensitive areas. It should be used at the stage of pre-feasibility studies of major projects and later in their stability monitoring, when required conditions of application are met.

Earthen Dike Leakage at the Dead Sea

The Dead Sea is a terminal lake located in the biggest pull-apart basins punctuating the Jordan-Dead Sea Transform. It is the lowest place on Earth (428 m bsl, 2014). The coastal areas are crossed by complex faulted zones and are characterized by highly karstic and fractured rock formations genetically connected with faults. Climate conditions range from semi-arid to arid. The potential evaporation rate is about 2500 mm/year. The riparian states withdraw large percentages of their fresh water from the Jordan River, the main tributary of the Dead Sea. A downward trajectory of the lake level was first noticed in the 1960s. Then, it has been dropping at an increasing rate: from about 60 cm/year in the 1970s up to 1.5 m/year in the 2010s. The magnitude of the shoreline withdrawal can reach several kilometers. Most of the new empty spaces have been progressively used by two mineral companies to build up salt evaporation ponds. From the early 1980s, sinkholes, subsidence and later landslides have appeared at an increasing rate all along the coast. In the 1990s, ground collapses started impeding the industrial development of the Arab Potash Company. Since then, security engineers are fighting bitterly against the multi-facetted salt karst issues to preserve their dikes. Here, sinkholes and subsidence leading to dikes leakage have a significant economic impact. The degradation of the Dead Sea coast is worsening and an early warning system to help avoiding further losses as much as possible should be set up rapidly.

Salt Tectonics of the Lisan Diapir Revealed by Synthetic Aperture Radar Images

1.1 General setting In the Oligocene, the Africa-Arabia plate broke up separating Arabia and Sinai as individual plate and sub-plate. Since then, the Arabian plate moves northward along the Jordan Dead Sea Transform (JDST) fault more rapidly than the Sinai sub-plate. This left-lateral strike slip movement (Figure 1) had displaced Early Miocene dykes across the fault zone up to 100 km (Quennell, 1958; Freund et al., 1970; Garfunkel et al., 1981) and had resulted in the development of rhomb-shaped grabens such as the Dead Sea pull-apart basin along the main fault (Figure 1, inset). The Dead Sea Basin is the largest pull-apart along the JDST fault. It is about 150 km x 15 km. Repeated structural subsidence resulted in the accumulation of sedimentary rocks as much as 10 km thick (Garfunkel and Ben Avraham, 1996). Inside the basin, two sets of faults, both oriented roughly N-S, can be recognized (Figure 1, inset). The first set is the extension of the northern and southern segments of the JDST fault, forming the pull-apart basin (Ben Avraham, 1997; Garfunkel, 1997). These faults are accommodating most of the horizontal motion of the JDST fault. The second set is constituted by the transverse faults, oriented NNW-SSE, that cross obliquely the basin at interval of 20-30 km. Between these faults, the basin infill is slightly back-tilted toward the south with no large deformations (Gardosh et al., 1997; Ben Avraham, 1997; Al Zoubi and ten Brink, 2001). Strong deformations are known only near the diapirs formed by the salt of the Sedom Formation (2 km thick). The Sedom formation formed from the late Miocene to the Pliocene (5.3 2.5 Ma). It is composed of 75% rocksalt which arrived via marine ingression from the Mediterranean and Red Seas. This flooding has ceased, however, with a rise of intrusive rock in the Araba and Jezreel valleys (Figure 1). The rocksalt is interbeded with anhydrite and gypsum, reddish dolomite, silt, sand and clay. Since the early Miocene, the center of sedimentary deposition existed where the Lisan area (Figure 1, inset) is currently located. During the Pliocene excessive accumulation of sediment caused a diapiric upward movement of accumulated lower-density sediment to begin, thus forming several salt

Very High Resolution ground displacement mapping and monitoring over the Lisan Peninsula: Preliminary Results

The Lisan peninsula is about 15 by 25 km . Two well-contrasted zones are distinguished: a triangularshape tableland corresponding to a former “peninsula”, at the time when the Dead Sea was composed of two sub-basins connected by the shallow Lynch strait and a wave-cut platform that emerged from the 1970s. Since the 1980s, the Dead Sea is only constituted by the northern deeper sub-basin.

The Dead Sea Subsidence and Sinkhole Disasters, over Two Decades of Monitoring and Studies. It Is Time for an Early Warning System Now!

As a consequences of the rapid lowering of the Dead Sea water level, which began in the 1960s, parts of the Dead Sea costal areas, could be considered as the most rapidly plagued with subsidence problems in the world. Yet some of these areas on the Jordanian half of the Dead Sea are becoming the focal point of Jordan’s touristic development efforts and plans which will potentially implicate billions of US

A 48-kyr-long slip rate history for the Jordan Valley segment of the Dead Sea Fault

s. Even before the multiple diversions of most the used to become Dead Sea water, the area is known to be geologically sensitive with possible, both natural and induced hazard concerns. Important parts of the coastal area is undergoing rapid and accelerating subsidence and sinkholes proliferation phenomena Further more the areas tectonic setting and conditions are further complicated by this induced and generalized subsidence phenomena which led during the last few decades to the development of a quite threatening situation.