Sinkholes of the Dead Sea Basin: A Result of Anthropogenic Disturbance to Nature and Sign for More and Greater Hazards

Abstract

Over the last few decades, thousands of sinkholes have developed at an increasing pace along the western 9 and eastern shores of the Dead Sea. Recent studies indicate that the number of sinkholes in the Dead Sea Basin 10 (DSB) has reached more than 6,000, with 1-10 m deep and up to 25-30 m in diameter, on average, each. These 11 sinkholes can open-up suddenly and swallow whatever found above them, resulting in an area that looks like an 12 earthquake zone. Sinkholes in the DSB are formed when a subterranean salt layer that once bordered the Dead Sea is 13 dissolved by underground freshwater that follows the migration of the saltwater-freshwater interface, due to 14 receding water level of the Dead Sea. Consequently, large areas of land are subsiding, causing the formation of 15 sinkholes in the region. Also, based on the fact that the Dead Sea's region is tectonically and seismically active, as it 16 is greatly affected by the Dead Sea Transform Fault System in the region, sinkholes can also be evolved as a result 17 of tectonic and seismic activities. Nevertheless, sinkholes, as geomorphologic features occurring in the DSB, 18 represent the most remarkable evidence of the brutal interferences of humans in the Dead Sea, especially sinkholes 19 started to appear remarkably and frequently in the last half a century only. They present a serious problem to the 20 Dead Sea's region, as they have led to damages in the infrastructures, and have threatened the safety of humans. 21 Large coastal areas along the Dead Sea shores on both sides of the Sea have already been totally closed to access, 22 because occurrence of more sinkholes is continually developing and rapidly increasing in number. This paper 23 investigates and discusses the occurrence of sinkholes in the Dead Sea Basin, geomorphologically, geologically, 24 seismically, limnologically, and socioeconomically, as well as with respect to the steady decline, at alarming rate, of 25 the Dead Sea's water level and the continuous shrinkage of its surface area, as the Dead Sea's water level has been 26 declining, on average, one meter per year just during the last 50 years or so. Also, the sinkholes' occurrence in the 27 DSB is investigated and discussed, with respect to tectonics and seismicity affecting the region. The results indicate 28 that more attention should be paid to this phenomenon-the rapid and intensive occurrence of sinkholes in the Dead 29 Sea's region-since it is a serious and dangerous disaster, affecting the Dead Sea Basin itself and its surrounding 30 environment. Unfortunately, this disaster is predominantly caused anthropogenically, as a result of the decline of the 31 Dead Sea's water level caused by humans' activities. So, this problem can be avoided or possibly reduced if man 32 would think about nature's protection rather than about his own interests. 33