SAR Interferometry for Sinkhole Early Warning and Susceptibility Assessment along the Dead Sea, Israel

Abstract

During the past three decades, the Dead Sea (DS) water level has dropped at an average rate of ~1 m/year, resulting in the formation of thousands of sinkholes along its coastline that severely affect the economy and infrastructure of the region. The sinkholes are associated with gradual land subsidence, preceding their collapse by periods ranging from a few days to about five years. We present the results of over six years of systematic high temporal and spatial resolution interferometric synthetic aperture radar (InSAR) observations, incorporated with and refined by detailed Light Detection and Ranging (LiDAR) measurements. The combined data enable the utilization of interferometric pairs with a wide range of spatial baselines to detect minute precursory subsidence before the catastrophic collapse of the sinkholes and to map zones susceptible to future sinkhole formation. We present here four case studies that illustrate the timelines and effectiveness of our methodology as well as its limitations and complementary methodologies used for sinkhole monitoring and hazard assessment. Today, InSAR-derived subsidence maps have become fundamental for sinkhole early warning and mitigation along the DS coast in Israel and are incorporated in all sinkhole potential maps which are mandatory for the planning and licensing of new infrastructure.

Multi- and inter-disciplinary approaches towards understanding the sinkholes’ phenomenon in the Dead Sea Basin

“…As seen in Fig. 6, the dramatic decline of the Dead Sea's water level for the period of ≈ 40 years (≈ 1978-2018) is strongly associated with a dramatic increase in the number of sinkholes occurred in the DSB [165]. This represents strong linkage between the two phenomena-the decline of the Dead Sea's water level and the frequent increase of the number and size of the sinkholes in the DSB.…”

“…Detecting minute precursory subsidence. Mapping zones susceptible to future sinkholes' formation [28,30,165] Nano-seismicity and microseismic activity monitoring Monitoring of subsurface material failures before sinkhole collapse. Vibrations produced by falling stones in the underground cavities Detecting the extremely low-energy signals produced by cavitation in unconsolidated layered media.…”

Detection of sinkhole occurrence, experiences from South Africa

“…In Fig. 2 the spatial distribution of 1100 events that occurred during the last four decades in the area south of Pretoria (Oosthuizen and Richardson, 2011). The occurrence of this event was a motivation to extend the research on sinkhole prone areas identification for the Centurion region.…”

Ground Deformations Controlled by Hidden Faults: Multi-Frequency and Multitemporal InSAR Techniques for Urban Hazard Monitoring

“…Often, the subsidence of ground surfaces can be the result of the natural compaction of sediments or caused by anthropological activities like the extraction of groundwater, geothermal fluids, oil, gas, coal and other solids through mining [6]. Even if the hazard associated with subsidence is often different from the ones related to sudden events like earthquakes [7] because of their influence over a wide area, or like sinkholes formation, because of the limited extension of the affected area [8], the damages connected to surface slow sinking events are, however, extensive and with impacts across wide regions. Ciudad Guzmán (CG) is located in the Colima Volcanic Complex, near the active volcano Fuego de Colima [9] (Figure 1).…”