late quaternary geological history of the dead sea area israel abstract a 34 5 m borehole which was drilled near the dead sea coast altitude 394 m in the southern part of the fan delta of wadi zeelim reveals the geological history of that area from the latest pleistocene to present the depositional time frame is based on six 14c dates and two u th dates an erosional or nondepositional period is implied by the hiatus between 21 100 yr b p u th age depth 33 m and 11 315 yr b p 14c age depth 32 m a subsequent arid phase is recorded by a 6 5 m thick layer of halite based on 14c dates this phase relates to the abrupt younger dryas cold period reported in temperate to polar regions the fragility of the environment in this region is indicated by the fact that the region experienced such a severe short aridification phase less than 1000 yr evidence of which is found widely in the desert fringes of the middle east and north africa the aragonite found in most of the holocene section indicates that the well site was covered by the lake for most of the holocene exceptions are the intervals at 0 3 and 10 14 m depths which represent low stands of the lake

will the dead sea die the level of the dead sea the lowest surface on earth is currently declining at a rate of 0 8 m yr and has dropped about 20 m since the beginning of the twentieth century it reached 410 m in 1997 we address the question of whether the level of the dead sea will continue to decline a numerical model developed in this study to determine the water balance accounts for the increase in salinity and the concomitant decrease in the rate of evaporation that accompanies reduction in the activity of the water simulations based on ranges of water withdrawal scenarios suggest that the dead sea will not die rather a new equilibrium is likely to be reached in about 400 yr after a water level decrease of 100 to 150 m

salt karst and tectonics sinkholes development along tension cracks between parallel strike slip faults dead sea jordan this work deals with the tectonic interpretation of an alignment of more than 300 sinkholes stretching along the jordanian coast of the dead sea ghor al haditha area its dimensions are 6 km long with a width of 600 m sinkholes appeared during the last decades as a consequence of the very rapid lowering of the lake level the linear shape was inferred from ground collapse inventories carried out between 1991 and 2008 the lineament is replaced and analyzed in its structural setting at regional and local scales its direction n 24 e is sub parallel to the ones displayed by many focal mechanisms especially the one associated with the earthquake of the 23 april 1979 mb 5 1 n 20 e 5 which is representative of all focal mechanisms calculated on a fault plane compatible with the general direction of the jordan dead sea transform fault system for the east coast of the dead sea area the alignment of sinkholes is constituted by 13 minor linear segments separated by as many empty spaces four minor linear units present an en echelon arrangement from which one can deduce the presence of a local extensional stress field in this context the sinkhole locations provide information of subsurface discontinuities interpreted as hidden fractures in a close future such results could support the work of decision makers and engineers in the projected development of the area copyright 2009 john wiley sons ltd

geomorphology and natural hazards in karst areas a review 1 introductionsince human beings started to colonise the world slowly migrat ing in multiple directions from the african rift and ultimatelyreaching the southernmost territories of the americas they haveinteracted with the natural environment using its resources and suf fering from its hazardous processes survival of mankind was possiblethanks to its ability to adapt to an ever changing environment and itscapability to learn and communicate the new ndings from the ear liest times geomorphic features and processes were an essential partof social survival crozier et al 2011 in karst terrains caves wereused as shelters as well as burial and sacred places playing an instru mental role in the day to day struggle for survival especially duringthe ice ages fig 1 spectacular karst landmarks such as big cave en trances blue karst springs deep collapse sinkholes cenotes or rockarches just to name a few have often become part of the naturaland supernatural heritage of our ancestors in prehistoric times the human impact on the karst environmentwas very limited like the probability of properties and people beingdamaged by karst processes e g subsidence ooding both impactsandhazardsinkarstterrainshaveincreaseddramaticallyover thelasttwo centuries along with the exponential increase in population andour capability to modify the natural environment largely related tothe economic and technological development of the societies an in creasing number of scientists consider that humans are nowadaysthe most effective geomorphic agent and a prime factor in landscapeevolution zalasiewicz et al 2010 price et al 2011 in fact the for mal de nition of the anthropocene as a new epoch of the geologicaltime scale characterised by a signi cant and global human impact onthe earth s ecosystems is being debated at the present time around25 of the earth s population lives on or nearby karst areas ford andwilliams 2007 and the increasing exploitation of karst resources such as water and building material is leading to severe environmen tal impacts and unsustainable situations drew and hotzl 1999 gunn 2004 unfortunately the number of karst areas affected bywater pollution landscape degradation and other impacts is growingveryrapidly additionally thedamagecausedbyhazardouskarstpro cesses especially subsidence sinkholes beck 2003 waltham et al 2005 gutierrez et al 2008a will most likely keep on increasing exposed human elements augment and anthropogenic changes inthe karst systems frequently result in hazard enhancement karstgeomorphologists and hydrologists can play a decisive role in pre venting natural disasters in karst areas particularly those inducedby human activities dams with leakage and sinkhole problems milanovic 2000 cooper and gutierrez 2011 mines and tunnelsaffected by ooding and subsidence li and zhou 1999 autin 2002 casagrandeet al 2005 luchaetal 2008 high speedrailwaysbuilt in sinkhole prone areas guerrero et al 2008 or developmentof sinkholes at huge rates induced by lake level yechieli et al 2006 or water table sprynskyy et al 2009 declines the importance of properly managing karst areas and mitigatingthe detrimental effects caused by human activities on these inherentlysensitive environments has been boosted by a series of conferencesand projects since the early 1990s ford 1993 williams 1993 pariseet al 2008 2009 raising public awareness on the need to protectour endangered natural resources especially in developed countries has promoted the production of karst speci c environmental impactassessments veni 1999 recently severalapproacheshavebeenpro posedtoassessthedegreeofhuman induceddisturbanceinkarstareas van beynen and townsend 2005 calo and parise 2006 de waele 2009 north et al 2009 although these studies are essential for apropermanagementofthekarstresources theymaybefutileifnotfol lowed by adequate administrative decisions and regulations 2 karst geomorphology2 1 karst processeskarst is characterised by the predominance of rock dissolution overmechanical erosion and is typical of present temperate cold andwarm and tropical environments ford and williams 2007 in karstterrains surface and subsurface geomorphology and hydrology arelargely governed by dissolution of carbonate and or evaporite rocks in the most classical common situation surface waters acidi ed byco

fault dissolution front relations and the dead sea sinkhole problem abstract there are two conflicting models of sinkhole development along the dead sea ds the first one considers structural control on sinkholes constraining them to tectonic lineaments this hypothesis is based on seismic reflection studies suggesting that sinkholes are the surface manifestations of active neotectonic faults that may serve as conduits for under saturated groundwater enabling its access across aquiclude layers another hypothesis based on results of multidisciplinary geophysical studies considers the salt edge dissolution front as the major site of sinkhole formation this hypothesis associates sinkholes with karstification of the salt edge by deep and shallow undersaturated groundwater our recent seismic reflection and surface wave studies suggest that salt formed along the active neotectonic faults sinkholes form in a narrow strip 60 100 m wide along a paleo shoreline constrained by faults and alluvial fans which determined the edge of the salt layer this scenario reconciles the two major competing frameworks for sinkhole formation

flow dynamics and salt transport in a coastal aquifer driven by a stratified saltwater body lab experiment and numerical modeling this paper examines the transient development and the steady state configuration of groundwater within a coastal aquifer adjacent to a stratified saltwater body such systems consist of three different water types the regional fresh groundwater and low and high salinity brines forming the upper and lower water layers of the stratified water body respectively the dynamics location and the geometry of the interfaces and the density driven circulation flows that develop in the aquifer are examined using laboratory experiments and numerical modeling at the same scale the results show that the transient intrusion of the different water bodies into the aquifer takes place at different rates and that the locations of the interfaces between them change with time before reaching steady state under steady state conditions both the model and the experiments show the existence of three interfaces between the three water types the numerical model which is calibrated against the salinity distribution and groundwater discharge rate in the laboratory experiments allows the quantification of the flow rates and flow patterns within the aquifer these flow patterns which cannot be derived from laboratory experiments show the transient development of three circulation cells which are confined between the three interfaces these results confirm the hypothesis that has been previously suggested based solely on a steady state numerical modeling defined by a conceptual understanding parametric analysis shows that the creation of three circulation cells and three interfaces is limited to certain conditions and defines the ranges for the creation of this unique system

quantitative assessment of in situ salt karstification using shear wave velocity dead sea abstract the dead sea ds coastal areas have been dramatically affected by sinkhole formation since around 1990 such sinkholes along both israeli and jordanian shores are linked to karst cavities that form through slow salt dissolution a quantitative estimate of such in situ salt karstification would be an important indicator of sinkhole hazard one of the indications of salt karstification is its increased hydraulic conductivity caused by the development of dissolution cavities forming conducting channels within the salt layer we measured the hydraulic conductivity k versus shear wave velocity vs of ds salt in situ for estimating the actual salt karstification in areas of sinkhole development these parameters were measured with the magnetic resonance sounding mrs and multichannel analysis of surface waves masw methods respectively understanding of the field relationships was augmented by similar inter relations obtained in the laboratory on samples of ds salt in situ salt velocities vs vary from 750 m s to over 1650 m s while hydraulic conductivity k in the same zones varies between about 10 4 m s to slightly over 10 8 m s both field and laboratory k and vs values fit the exponential function ln k 0 0045 vs 5 416 with a determination coefficient r2 of 0 88 a classification based on vs and k was generated for salt conditions and the corresponding degrees of sinkhole hazard which was verified in the mineral beach sinkhole development area the mapping of sinkhole sites shows that they form within highly conductive zones with k 5 5 10 5 it is suggested that this methodology with some modification can be used for evaluating the conductive properties of karstified rock and associated sinkhole hazards

experimental study on the critical triggering condition of soil failure in subsidence sinkholes subsidence sinkholes in karst terrain are a common geological hazard which can lead to natural disasters in the natural and built environment groundwater ingress is the main factor leading to subsidence previous research has focused on the qualitative analysis of the influence of groundwater although limited research into critical triggering conditions of groundwater has been undertaken quantitatively water seepage into soil is the starting condition in the development of subsidence sinkholes this paper focuses on testing the anti permeability strength as the critical triggering condition in the formation of subsidence sinkholes and develops a design and methodology to test its value quantitatively the methodology is applied in an industrial park of guilin china to assess the probability of forming subsidence sinkholes results indicate that there is a low susceptibility to the formation of subsidence sinkholes under current conditions in the ground truth investigation

human induced geological hazards along the dead sea coast the dead sea is a terminal lake whose level is currently dropping at a rate of about 1 m per year due to the over exploitation of all its tributaries the lowering started about four decades ago but geological hazards appeared more and more frequently from the end of the 1980s the water level lowering is matched by a parallel groundwater level drop which results in an increasing intensity of underground and surface water flow the diagonal interface between the dead sea brine and the fresh groundwater is pushed downwards and seawards nowadays sinkholes subsidence landslides and reactivated salt karsts affect wide coastal segments until now mainly infrastructures were damaged and few people animals were injured but the ongoing development of tourism in this very attractive situation will increase the risk if precautionary measures are not included in the development plans this paper discusses the main observations made all around the dead sea and shed a light on the differences between the geological hazards of the western shore israel palestinian authority and the eastern shore jordan it is the first attempt to bring together an overview of the human induced geological hazards encountered along the dead sea coast

velocity resistivity versus porosity permeability inter relations in dead sea salt samples abstract this study is intended to investigate dead sea ds salt porosity permeability hydraulic conductivity inter relations as well as their relationship to geophysical parameters such as compression and shear wave velocities vp vs respectively and specific resistivity x in laboratory and field conditions to estimate representative properties affected by porosity changes during sinkhole development some 41 salt samples were subjected to porosity measurements and 25 samples were tested to reveal hydraulic conductivity the salt of the coastal dead sea area composed of halite is revealed in 10 200 10 800 year old layers the halite commonly appears as rock salt the 7 30 m thick salt unit is located below the groundwater table at depths of 20 50 m from the surface salt layers are very conductive hydraulically and water saturated with the ds brine is of very high salinity with total dissolved solids tds of 340 380 g l two types of salt have been studied crystalline transparent salt cts distributed along the entire ds s western shore and white massive salt wms found locally along the southern ds and along the dike salt porosity measured in samples varies in the range of 5 21 whereas hydraulic conductivity varies between 10 5 to 10 9 m s density is changed in the range of 1681 2116 kg m 3 in wet samples and between 1638 and 2106 kg m 3 in dry samples during the laboratory testing of ds salt samples we have measured the following geophysical parameters vp 3700 4460 m s vs 1900 2620 m s and x 2 100 m on the other hand our previous field studies based on s wave seismic refraction surface wave prospecting swp and transient electromagnetic tem methods have shown that in in situ salt velocities vp range between 2900 and 4240 m s vs varies between limits of 750 m s to more than 1650 m s and x is of 0 8 to 2 5 m these values are considerably less than the analogous parameters measured in the salt samples the same conclusion has been made from the comparison of salt sample properties and borehole logging both studied by ultrasonic method geophysical data testify that in situ porosity calculated using relationships obtained during this study exceeds those in the laboratory samples especially in zones of heightened voidness where it is 25 hydraulic conductivities in the same zones exceed a value of 10 6 m s and even 10 5 m s we expect that in larger salt volumes these parameters can yet increase

contrastive analysis of karst collapses and the distribution rules in northern and southern china in northern and southern china there are two different territorial systems of karst collapse because of the differences in basic geological conditions groundwater dynamic conditions and climatic factors the karst collapses are different in northern china from those in southern china in types distribution characteristics development density scope and formation mechanism based on analysis of statistical data in bulk and analysis of basic rules of the karst collapses in china this paper systematically analyzed the basic geological conditions groundwater dynamic conditions and climatic conditions both in north and south when studied and concluded the discrepancy in features scales density regional distribution rules formation mechanism etc the contrast and rules concluded will be of important significance and have great implication value to the exploration and prevention of karst collapse planning and layout of relevant project construction

sinkhole swarms along the dead sea coast reflection of disturbance of lake and adjacent groundwater systems more than a thousand sinkholes have developed along the western coast of the dead sea since the early 1980s more than 75 of them since 1997 all occurring within a narrow strip 60 km long and 1 km wide this highly dynamic sinkhole development has accelerated in recent years to a rate of 150 200 sinkholes per year the sinkholes cluster mostly over specific sites up to 1000 m long and 200 m wide which spread parallel to the general direction of the fault system associated with the dead sea transform research employing borehole and geophysical tools reveals that the sinkhole formation results from the dissolution of an 10 000 yr old salt layer buried at a depth of 20 70 m below the surface the salt dissolution by groundwater is evidenced by direct observations in test boreholes these observations include large cavities within the salt layer and groundwater within the confined subaquifer beneath the salt layer that is undersaturated with respect to halite moreover the groundwater brine within the salt layer exhibits geochemical evidence for actual salt dissolution na cl 0 5 0 6 compared to na cl 0 25 in the dead sea brine the groundwater heads below the salt layer have the potential for upward cross layer flow and the water is actually invading the salt layer apparently along cracks and active faults the abrupt appearance of the sinkholes and their accelerated expansion thereafter reflects a change in the groundwater regime around the shrinking lake and the extreme solubility of halite in water the eastward retreat of the shoreline and the declining sea level cause an eastward migration of the fresh saline water interface as a result the salt layer which originally was saturated with dead sea water over its entire spread is gradually being invaded by fresh groundwater at its western boundary which mixes and displaces the original dead sea brine accordingly the location of the western boundary of the salt layer which dates back to the shrinkage of the former lake lisan and its transition to the current dead sea constrains the sinkhole distribution to a narrow strip along the dead sea coast the entire phenomenon can be described as a hydrological chain reaction it starts by intensive extraction of fresh water upstream of the dead sea continues with the eastward retreat of the lake shoreline which in turn modifies the groundwater regime finally triggering the formation of sinkholes

the solubility of halite as a function of temperature in the highly saline dead sea brine system the dead sea brine is characterized by high ionic strength 9 10 m and a ca cl composition the lake is currently saturated with respect to aragonite gypsum and halite harned s rule is applied to calculate the saturation index of halite in the dead sea brine system this system includes brines at ionic strengths in the range of 9 l 6 1 derived from evaporating dead sea brine to facilitate the calculation we determined new interaction coefficients experimentally these were found to be a function of the ionic strength of the solution as well as of the temperature 25 c anaa mgc12 0 002611 0 00905 anac1 caci 0 001501 0 00650 3 5 c anac l m cl 0 002831 0 01972 anacl caci 0 002071 0 01851 50 c anaci m l 0 002261 0 01416 anaci cacl 0 001561 0 01315 the new parameters are used to predict the effect of temperature on halite precipitation in the lake from both the evaporating surface layer and the entire upper water body the calculated weight of halite expected to precipitate before the onset of carnallite precipitation is on the order of lo o t at the present rate of evaporation at least 120 yr will pass before that point is reached

detection of subsurface brines freshwater bodies and the interface configuration in between by the time domain electromagnetic method in the dead sea rift israel high radon fluxes in the seismically active dead sea rift seem to be affected by the hydrological system and the different salinities of groundwater bodies involved the time domain electromagnetic tdem method was employed to delineate those different bodies and the configuration of the interfaces between them the present hydrological system and the related brines and interfaces are controlled by the dead sea base level presently at 408 m below msl tdem measurements detect low resistivity 1 ohm m units representing brines and the interface between them as well as the overlying fresher water bodies in addition high resistivity freshwater units are also detected underlying the brines related herein to a multiple hydrological system low resistivity brines detected above the present base level are interpreted herein as yet unflushed ones which correspond to a former higher base level higher sequences below historical sixteenth century base levels are already devoid of brines which gives an indication as to the rate of flushing

locating water filled karst caverns and estimating their volume using magnetic resonance soundings magnetic resonance sounding mrs is a geophysical technique developed for groundwater exploration this technique can be used for investigating karst aquifers generally the study ofakarstrequiresa3dfieldsetupandcorrespondingmultichannel data acquisition instruments now only single channel mrs equipment is available i e the time needed for a 3d mrs field survey is multiplied by a factor of four or five where karst caverns are natural hazards as in the dead sea coastal area at nahal hever israel even an approximate localization of potentially dangerous zones and a corresponding estimation of the hazard dimensions are useful we studied numerically the accuracy of mrs estimations of the volume of different 3d targets around nahalhever shiftinga3dtargetinsidethemrsloopandcalculating the volume estimation errors for each target position the calculations covered targets of different sizes the size and position of a target being unknown factors in a field survey the numerical data were considered as random values to be analyzed statistically using a 1d approximation of the mrs solution and assuming a 100 100 m 2 mrs loop the volume of a 3d target under nahal hever conditions is estimated within a 75 error when the target is smaller than the mrs loop and within a 50 error when the target size is about the same as the mrs loop the lower threshold of karst cavity detection with mrs is about 6500 m3 for such estimation only one sounding is

pre existing caverns in salt formations could be the major cause of sinkhole hazards along the coast of the dead sea since 1990 hundreds of sinkholes have appeared along the coast of the dead sea in the literature the rapid development of sinkholes is explained as a result of a drop in the level of the dead sea this model assumes very fast dissolution of large volumes of salt and the creation of new caverns that cause sinkholes in 10 to 20 years however the results of our geophysical study do not confirm the fast dissolution assumption to explain the available field observations we propose the following model 1 slow dissolution of salt much longer than 20 years with the creation of caverns without development of sinkholes 2 sinkhole development is triggered by the lowering of the groundwater level because the rocks overlying the salt formation become unsaturated 3 the time of sinkhole appearance is controlled by the mechanical properties of the rocks that overlie pre existing caverns

late holocene lake levels of the dead sea this work presents a high resolution lake level record of the late holocene dead sea a hypersaline terminal lake whose drainage basin encompasses both mediterranean and hyperarid climatic zones the lake level curve reflects the regional hydrologic variations in the drainage basin which in turn represent the levant paleoclimates the curve is based on 46 radiocarbon ages of organic remains from well exposed sedimentary sequences along the dead sea shores these sequences record fluvial and lacustrine depositional environments the paleolakeshores are marked by shore ridges coarse sand units and aragonite crusts in the modern dead sea such features indicate the exact elevation of the shore the late holocene dead sea level fluctuated within the range of 390 to 415 m below sea level mbsl for most of the time the lake was below the topographic sill 402 mbsl separating the northern and southern basins of the dead sea and was confined to the deep northern basin nevertheless short term rises in the late holocene dead sea level caused the flooding of the shallow and flat southern basin highstands occurred in the second and first centuries b c and the fourth century a d during the roman and early byzan tine periods respectively in the eleventh and twelfth centuries a d during the crusader period and at the end of the nineteenth century a d the rises mark a significant change in the annual rainfall in the region which likely exceeded the instrumentally measured modern average the curve also indicates drastic drops that exposed the sedimentary sequences to erosion the oldest and probably deepest drop in the lake level culminated during the fifteenth and fourteenth centuries b c after a retreat from a higher lake stand the longest lowstand occurred after the byzantine period and continued at least until the ninth century a d this arid period coincided with the invasion of moslem arab tribes into the area during the seventh century a d the dramatic fall of the dead sea level during the twentieth century is primarily artificial and has been caused by the diversion of runoff water for the drainage basin but the magnitude is not considered exceptional for the late holocene although the past drops in the lake never exceeded the modern artificial drop rates they do represent extreme arid conditions that occurred frequently over the past several thousand years

aquifer characteristics derived from the interaction between water levels of a terminal lake dead sea and an adjacent aquifer the water level of the dead sea a terminal hypersaline lake total dissolved solids approximately 340 g l has decreased at an average rate of 0 5 m yr since 1960 and by 0 8 m yr between 1981 and 1989 the dramatic long term water level variation of the dead sea and the seasonal short term fluctuations are accompanied by parallel variations of groundwater levels in an adjacent aquifer a general methodology based on a simplified yet reliable one dimensional flow model together with continuous measurements of groundwater levels in observation wells enables analysis of aquifer structural and hydraulic properties furthermore this analysis enables prediction of future groundwater levels in unconfined and confined aquifers due to future changes in lake levels

geophysical prediction and following development sinkholes in two dead sea areas israel and jordan geophysical methods seismic refraction srfr electrical resistivity tomography ert and microgravity were applied to the dead sea ds sinkhole problem in the ein gedi area at the earlier stage of the sinkhole development 1998 2002 they allowed determining the sinkhole formation mechanism and localizing the sinkhole hazardous zones the srfr method permitted to delineate the underground edge of a salt layer at the depth of 50 m the salt edge was shaped like the sinkhole line on the surface it was concluded that the sinkhole development is linked to the salt edge geoelectrical quasi 3d mapping based on the ert technique detected large resistivity anomalies with 250 300 m2 diameter and 25 35 m deep the ein gedi area has been also mapped by the use of microgravity method the residual bouguer gravity anomaly map shows negative anomalies arranged along the edge of the salt layer those gravity anomalies overall are very similar in plan to the resistivity distribution in this area the results of forward modeling indicate that both high resistivity and residual gravity anomalies are associated with a subsurface decompaction of the soil mass and deep cavity at the sinkhole site following monitoring of the sinkhole development carried out by the geological survey of israel confirmed our suggestions the drilling of numerous boreholes verified the location of the salt edge geographical information system gis database testifies that during 2003 2009 new sinkholes are continuing to develop along the salt edge within a narrow 50 100 m wide strip oriented approximately in north south direction slightly parallel to the shoreline no promotion in west east direction perpendicularly to the ds shoreline was observed in israel collapse of sinkholes and their clustering have been occurred within the area of high resistivity anomaly and negative residual gravity anomaly similar studies carried out at the ghor al haditha area jordan have shown that sinkholes there are also arranged along the winding line conforming to the salt edge in this area sinkholes are slowly moved to the dead sea direction results of geophysical studies in numerous ds sites indicate similar sinkhole development it allowed generating of the sinkhole formation model based on ancient 10 000 11 000 year old salt belt girding the dead sea along its shores

sustainable development and anthropogenic induced geomorphic hazards in subsiding areas in many areas of the world subsidence related to the lowering of the water table is modifying the landscape and provoking costly environmental hazards this article is protected by copyright all rights reserved we consider the dead sea the earth s lowest lake as a model its water level was 395 m bmsl in the 1960s due to water diversions in the catchment area as of 2016 the level has dropped to about 430 m bmsl here as in other parts of the anthropocene world from china to iran to turkey to canada and the united states consequences of human interventions are rapidly modifying the environment aggressive geomorphic processes leading to accelerated degradations are taking place and affecting landforms and infrastructures this article is protected by copyright all rights reserved in tectonic terms the lake is a pull apart basin resulting from the motion of the dead sea transform fault since the 1960s a slice of brine of about 35 km3 had been lost the water table is dropping more rapidly in the lake than in the coastal zone creating an ever increasing head difference consequently groundwater moves towards the sea to compensate for the imbalance provoking the reactivation of the area s paleo channels with subsidence sinkholes and landslides this article is protected by copyright all rights reserved since the 1980s industrial touristic infrastructure has covered newly emerging lands in geomorphic hazards prone areas of the coastal zone this article is protected by copyright all rights reserved time series analysis of high to very high resolution visible radar satellite images acquired from the 1970s to present revealed major landscape evolution such dynamic systems prevailing in the last decades permitted the study of human environment interactions to help minimizing their effects this article is protected by copyright all rights reserved major deformations of an industrial dike were analysed and quantified the results underline the necessity in the anthropocene of careful analysis of relevant data sources acquired before and during subsidence particularly in karst topography zones and prior to the development of major human activities in economically appealing environments around the world this article is protected by copyright all rights reserved

use of gpr method for prediction of sinkholes formation along the dead sea shores israel abstract it seems the highly saline conditions of the dead sea ds coast line are not favorable for the use of ground penetrating radar gpr method for detection of underground caverns before sinkhole formation short time prediction the location of the formed caverns within the salt layer significantly more than the penetration depth of the electromagnetic waves combined with the saline ds brine groundwater covering the salt layer from above characterized by low electrical resistivity makes the application of electromagnetic waves ew impossible however our experience has shown that gpr technique in its 2d and 3d modifications can be a very efficient tool to predict sinkhole susceptibility case histories of gpr studies in the mineral beach and nahal david sites are presented the gpr study has shown that the method is effective in both urban sites and at most of sites of human activities of the dead sea coast dwellings routes agricultural areas etc but it fails in areas composed of saline mud in the subsurface some areas lower than 400 m elevation the fan areas are composed of sandy gravel sediments and the penetrating depth of the electromagnetic waves varies but is usually limited to the first meters up to 8 10 m maximum to 13 15 m but in any case not deeper than the water table depending on the dielectric constant which as a rule is 4 25 in areas covered by dead sea mud penetration depth is limited to the first meter due to the low electrical resistivity of the sediments models of sinkhole formation and principles of cavity detection in the ds area are discussed to understand the fundamentals of gpr use for the prediction of sinkhole susceptibility

characterization of land degradation along the receding dead sea coastal zone using airborne laser scanning abstract the dead sea the lowest place on the earth s continents was at its highest level in 1896 reaching an elevation of 388 4 m below mean sea level m b m s l and 390 m in the early 1920s since then it has almost constantly been dropping reaching the level of 426 m b m s l in 2013 since the late 1990s its level has been decreasing by approximately 1 my 1 the rapid lake retreat accelerates large scale environmental deterioration including soil erosion land degradation rapid headcut migration and widespread development of collapse sinkhole fields these geomorphic elements threaten the natural environment and anthropogenic infrastructure we provide an overview of the geomorphic processes in the form of soil erosion channel incision land degradation and the development of collapse sinkholes we take advantage of the high resolution airborne laser scanning technology for three dimensional detection of surficial changes quantification of their volumes and documentation of the present state of the terrain with utmost accuracy and precision this type of information and the identification of future trends are vital for proper planning of any rapidly changing environment

anticipating and managing engineering problems in the complex karst environment karst environments are characterized by distinctive landforms and a peculiar hydrologic behavior dominated by subsurface drainage karst systems can be extremely complex heterogeneous and unpredictable due to the wide range of geological and hydrological controlling factors the great variability results in serious problems for engineers and in difficulties to characterize the karstified rock masses and in designing the engineering works to be performed the design and development of engineering projects in karst environments require specific approaches aimed at minimizing the detrimental effects of hazardous processes and environmental problems further karst aquifers that provide approximately 20 25 of the world s drinking water are extremely vulnerable to pollution due to the direct connection between the surface and the subsurface drainage the rapidity of the water flow in conduit networks and the very low depuration capability sinkholes are the main source of engineering problems in karst environments and may cause severe damage in any human structure the strategies and solutions that may be applied to mitigate sinkhole problems are highly variable and largely depend on the kind of engineering structure the karst setting and the typology and size of the sinkholes a sound geological model properly considering the peculiarities of karst and its interactions with the human environment is essential for the design of cost effective and successful risk reduction programs due to the unique direct interaction between surface and subsurface environments and the frequent ground instability problems related to underground karstification management of karst environments is a very delicate matter disregarding such circumstances in land use planning and development inevitably results in severe problems with high economic impacts karst environments require specific investigation methods in order to properly manage and safeguard the sensitive geo ecosystems and natural resources associated with them

identification and quantitative analysis of sinkhole contributing factors in florida s karst abstract sinkholes are one of the major geohazards in karst areas causing loss of life and significant economic loss as well sinkhole forming mechanism varies depending on the geological environment and florida s sinkholes are formed through the process of interaction between groundwater flow and cover soils the significance of this paper is 1 to identify key sinkhole contributing factors and 2 to quantify the impact of those factors on sinkhole formation particularly this study accounted for geomechanical factors that contribute to sinkhole raveling due to erosion and mechanical stability of overburden soils identification of key sinkhole contributing factors will allow developing a probabilistic sinkhole prediction model the study area was focused on east central florida where cover collapse sinkholes often occur uniform distribution transformation was employed for the quantitative analysis on each factor and then case studies with specific examples are then presented to validate the results of the quantitative analysis in conclusion the identified key factors are hydraulic head difference soil permeability thicknesses of aquifer systems and proximity to karst features e g existing sinkhole the critical permeability kcrit showing a rapid increase of sinkhole occurrence is about 20 cm h thickness and characteristics of cover soils seem a controlling factor of sinkhole types and the overburden thickness around 40 to 45 m tends to form the collapse type a multivariate regression analysis indicates that the thickness of the surficial aquifer system is the most significant factor and then the head difference and the proximity to karst features follow in order

actual extension of sinkholes considerations about geophysical geomorphological and field inspection techniques in urban planning projects in the ebro basin ne spain abstract aerial photographs historical cartographies and field inspection are useful tools in urban planning design on mantled karst because they permit a wide time interval to be analyzed in the case of zaragoza city several works have confirmed the interest of these approaches in configuring the urban planning code and therefore represent a promising technique nevertheless some caveats should be taken into account when using this kind of information a detailed analysis is presented comparing in a case study from the surroundings of zaragoza geomorphological historical analysis and field inspection with geophysical data field inspection in a noncultivated area permits the constraint of the presence of karst indicators below the geomorphological resolution of aerial photographs and shows results consistent with geophysical surveys the studied case shows an inner zone coinciding with the sinkhole mapped from aerial photographs that correlates with changes in the position of the substratum and changes in thickness of alluvial sediments the integrated analysis permits us to define an external subsidence ring around the geomorphological sinkhole whose surface is twice the size of the inner zone this outer ring is indicated by geometrical changes in gpr profiles increases of thickness of the conductive shallower unit toward the collapse and small collapses on marginal cracks these results support the higher extension of karst hazards linked to sinkholes with respect to their geomorphological expression and the needed detailed analysis to constrain the real sinkhole size or the use of security radii surrounding this surficial evidence when geomorphological data is used for the hazard analyses or the urban planning at karstic zones

collapse sinkholes and radar interferometry reveal neotectonics concealed within the dead sea basin 1 the dead sea ds pull apart basin is one of the more seismically active segments of the ds transform plate boundary in the last decade hundreds of collapse sinkholes have been formed along the ds coastlines in israel and jordan causing severe damage to the regional infrastructure the formation of these sinkholes is attributed to the dissolution of a buried salt layer by fresh groundwater due to the drop of the ds and the associated groundwater levels here we show that the sinkhole distribution combined with gradual land subsidence measured by radar interferometry insar track young fault systems suspected as active concealed within the fill of the ds rift this notion is supported by 1 sinkholes clustering along discrete lineaments with a striking trend similarity to that of the exposed rift margin faults 2 prominent discontinuities in seismic reflection profiles offsetting young sediments several kyrs old below sinkhole lines and 3 straight boundaries of gradual subsidence features that coincide with or parallel sinkhole lines combined the sinkhole lineaments and the insar measurements reveal a zigzag pattern of buried faults within the ds rift fill

hierarchic three dimensional structure and slip partitioning in the western dead sea pull apart 1 rifted basins are bounded by marginal belts with fault networks and flexures we analyze the internal structure of such a belt the western margins of the dead sea basin this basin is 150 km long 15 20 km wide with more than 10 km of sediment fill and it is currently subsiding due to slip of the dead sea pull apart the western margin of the dead sea basin is an elongated n s belt with an intricate three dimensional 3 d pattern of zigzag faults flexures and joints the dominant structures are four sets of oblique normal faults arranged in orthorhombic symmetry the faults are steep with prevalent strike directions of nnw and nne large flexures developed along and above these faults forming tilted blocks and localized asymmetric folds two sets of subvertical joints that dominate the area trend nne and nnw subparallel to the strikes of the dominant fault sets the parallel relations between these structures at all scales suggest that they formed during a single tectonic phase three dimensional fault modeling reveals a 3 d strain field with a large vertical shortening a minor horizontal shortening in n s direction belt parallel and a large horizontal e w extension basinward the calculated stress fields associated with the zigzag fault segments are compatible with the observed fault parallel flexures further the calculations predict the formation of local tensile belts above the faults and these tensile belts could explain the penecontemporaneous development of the two joint sets architecture similar to the western margins of the dead sea basin is likely to develop on rifted margins wherever 3 d deformation is required by the rifting kinematics

lake levels and sequence stratigraphy of lake lisan the late pleistocene precursor of the dead sea lake lisan the late pleistocene precursor of the dead sea existed from 70 000 to 15 000 yr b p it evolved through frequent water level fluctuations which reflected the regional hydrological and climatic conditions we determined the water level of the lake for the time interval 55 000 15 000 cal yr b p by mapping offshore nearshore and fan delta sediments by application of sequence stratigraphy methods and by dating with radiocarbon and u series methods during the studied time interval the lake level fluctuated between 340 and 160 m below mean sea level msl between 55 000 and 30 000 cal yr b p the lake evolved through short term fluctuations around 280 290 m below msl punctuated at 48 000 43 000 cal yr b p by a drop event to at least 340 m below msl at 27 000 cal yr b p the lake began to rise sharply reaching its maximum elevation of about 164 m below msl between 26 000 and 23 000 cal yr b p then it began dropping and reached 300 m below msl at 15 000 cal yr b p during the holocene the lake corresponding to the present dead sea stabilized at ca 400 m below msl with minor fluctuations the hypsometric curve of the basin indicates that large changes in lake area are expected at above 403 and 385 m below msl at these elevations the lake level is buffered lake lisan was always higher than 380 m below msl indicating a significantly large water contribution to the basin the long and repetitious periods of stabilization at 280 290 m below msl during lake lisan time indicate hydrological control combined with the existence of a physical sill at this elevation crossing this sill could not have been achieved without a dramatic increase in the total water input to the lake as occurred during the fast and intense lake rise from 280 to 160 m below msl at 27 000 cal yr b p

human induced hydrogeological changes and sinkholes in the coastal gypsum karst of lesina marina area foggia province italy abstract in 1930 a canal was excavated to connect the lesina lagoon with the adriatic sea modifying the track of the previous existing acquarotta canal the 1100 m long stretch of the canal situated next to the coast exposed unknown highly cavernous gypsum bedrock underlying a loose sandy cover during the last two decades a large number of cover collapse and cover suffosion sinkholes have formed along two bands situated next to the canal impinging the adjacent lesina marina residential area the area affected by subsidence has increased exponentially from 1999 to 2009 the tight spatial correlation between the sinkholes and the canal reveals that the subsidence phenomenon has been induced by the local hydrogeological changes caused by the canal in the coastal evaporite aquifer 1 local lowering of the average water table 2 deflection of the groundwater flow lines towards the canal and increase in flow velocity 3 amplification of the groundwater level oscillations largely controlled by the tidal regime 4 local reversals in the groundwater flow changing the canal temporarily from effluent to influent these changes in the hydrogeological functioning of the system have favoured both internal erosion and karstification processes hydrochemical evidence reveals that gypsum dissolution is a currently active process favoured by fresh water and sea water mixing and cation exchange processes most likely the partial replacement of a concrete lining in the canal by pervious gabions in 1993 provided more adequate conditions for the evacuation of the sediments filling the karst conduits accelerating internal erosion and sinkhole development

topographic constraints on the evolution and connectivity of titan s lacustrine basins the topography provided by altimetry sar topo and stereo radargrammetry has opened new doors for titan research by allowing for quantitative analysis of morphologic form using altimetry measurements we show that titan s maria are consistent with an equipotential surface but that several filled lakes are found to be hundreds of meters above this sea level suggesting that they exist in isolated or perched basins within a given drainage basin empty lake floors are typically higher than the liquid elevation of nearby lakes seas suggesting local subsurface connectivity the majority of titan s lakes reside in topographically closed sharp edged depressions whose planform curvature suggests lateral expansion through uniform scarp retreat many but not all empty lake basins exhibit flat floors and hectometer scale raised rims that present a challenge to formation models we conclude that dissolution erosion can best match the observed constraints but that challenges remain in the interpretation of formation processes and materials

overview of karst geo environments and karst water resources in north and south china the karst geological system in north china is different from that in the south due to differences in basic geological conditions and environment the karst evolutional pattern and karst water resources among other things are also different in the two regions this paper based on on site fieldwork and analysis of an extensive database of karst in china presents a systematic and contrastive analysis of karst geological environment and karst water resources in north versus south china highlights the differences between the two regions in basic karst geological conditions groundwater dynamics and karst water resources and concludes with the economic environmental and engineering implications of these differences these findings will be helpful for the strategic planning and decision making processes associated with exploitation of karst geological resources and with prevention and control of karst geological hazards

late holocene climates of the near east deduced from dead sea level variations and modern regional winter rainfall the dead sea is a terminal lake of one of the largest hydrological systems in the levant and may thus be viewed as a large rain gauge for the region variations of its level are indicative of the climate variations in the region here we present the decadal to centennialresolution holocene lake level curve of the dead sea then we determine the regional hydroclimatology that affected level variations to achieve this goal we compare modern natural lake level variations and instrumental rainfall records and quantify the hydrology relative to lake level rise fall or stability to quantify that relationship under natural conditions rainfall data pre dating the artificial dead sea level drop since the 1960s are used in this respect jerusalem station offers the longest uninterrupted pre 1960s rainfall record and jerusalem rains serve as an adequate proxy for the dead sea headwaters rainfall principal component analysis indicates that temporal variations of annual precipitation in all stations in israel north of the current 200 mm yr 1 average isohyet during 1940 1990 are largely synchronous and in phase 70 of the total variance explained by pc1 this station also represents well northern jordan and the area all the way to beirut lebanon especially during extreme drought and wet spells we a determine the modern and propose the past regional hydrology and eastern mediterranean em climatology that affected the severity and length of droughts wet spells associated with multiyear episodes of dead sea level falls rises and b determine that em cyclone tracks were different in average number and latitude in wet and dry years in jerusalem the mean composite sea level pressure and 500 mb height anomalies indicate that the potential causes for wet and dry episodes span the entire em and are rooted in the larger scale northern hemisphere atmospheric circulation we also identified remarkably close association within radiocarbon resolution between climatic changes in the levant reflected by level changes and culture shifts in this region

hidden sinkholes and karst cavities in the travertine plateau of a highly populated geothermal seismic territory tivoli central italy abstract sinkholes and other karst structures in settled carbonate lands can be a significant source of hazard for humans and human works acque albule the study area of this work is a plio pleistocene basin near rome central italy superficially filled by a large and thick deposit of late pleistocene thermogene travertine human activities blanket large portions of the flat territory covering most evidence from geological surface processes and potentially inducing scientists and public officials to underestimate some natural hazards including those connected with sinkholes to contribute to the proper assessment of these hazards a geomorphologic study of the basin was performed using digital elevation models dems recent aerial photographs and field surveys historical material such as old aerial photographs and past geomorphologic studies both pre dating the most part of quarrying and village building was also used together with memories of the elderly population this preliminary study pointed out the presence of numerous potentially active sinkholes that are at present largely masked by either quarrying or overbuilding where this first study pointed out the apparent absence of sinkholes in areas characterized by high density of buildings a detailed subsurface study was performed using properly calibrated electrical resistivity tomography ert and dynamic penetration measurements dpsh together with some borehole logs made available from the local municipality this second study highlighted the presence of sinkholes and caves that are this time substantially hidden to the resolution of standard methods and materials such as aerial photographs dems and field surveys active sinkhole subsidence in the acque albule basin may explain at least in part the frequent damages that affect numerous buildings in the area the main conclusion from this study is that the mitigation of sinkhole hazard in highly populated areas has to pass through a thorough search of hidden sinkholes that can be masked by the anthropocenic molding and blanketing of the territory for these purposes data from historical pre anthropocene documents as well as where possible subsurface investigations are fundamental

abrupt aridities and salt deposition in the post glacial dead sea and their north atlantic connection abstract abrupt arid events in the post glacial 17 4 10 kyr bp dead sea basin dsb were recorded by significant lake level declines in lake lisan and massive deposition of gypsum and salt between 17 4 and 16 kyr cal bp the lake level dropped from its late mis2 stand of 260 m below mean sea level m bmsl to 330 m bmsl depositing a thick sequence of gypsum between 16 and 15 kyr cal bp the lake level recovered but dropped abruptly again at 14 kyr cal bp to below 465 m bmsl probably the lowest late pleistocene stand then between 13 and 11 kyr cal bp the younger dryas time interval the lake rose above 400 m bmsl and declined at 11 10 kyr cal bp depositing a thick sequence of salt the abrupt lake level drops and salt deposition coincided with times of ice and meltwater discharges into the north atlantic na heinrich event h1 and meltwater pulse mwp1a similar coincidence between ice and meltwater discharges in the na e g h events and arid episodes at the levant was recorded during the colder last glacial period demonstrating a persistent effect of the north atlantic hydrology and sea ice advances on the levant climate the climatically turmoil post glacial period was accompanied by significant developments in human culture the collapse of the natufian culture during the bolling allerod and the rise of the pre pottery neolithic cultures ppn a and b around the 11 10 kyr cal bp salt deposition interval marking the initiation of the neolithic revolution in the region

the holocene climatic record of the salt caves of mount sedom israel mount sedom is a salt diapir on the southwestern shore of the dead sea which has been rising above the local base level throughout the holocene karst development within the salt body has kept pace with the rise forming subhorizontal cave passages with vertical shafts wood fragments found embedded in flood sediments that were deposited in the cave passages yielded 14c ages ranging from c 7100 to 200 bp a palaeoclimatic sequence was constructed based on parameters that include relative abundance of plant types or floral communities the elevations of the corresponding cave passages and the ratio of their width to present passage width the results were correlated to the holocene sedimentary sequence of the dead sea basin and other features associated with shifting lake levels moister climatic stages are indicated by relatively abundant wood remains by wide cave passages and by elevated outlets indicating high dead sea level arid periods are marked by a scarcity of wood remains by narrow cave pa

response to comment on dead sea drawdown and monsoonal impacts in the levant during the last interglacial epsl 412 235 244 2015

dead sea sinkholes an ever developing hazard sinkhole development along the western shore of the dead sea became a major concern in 1990 with the appearance of a series of holes 2 15 m diameter and up to 7 m deep in the newe zohar area one of these sinkholes below the asphalt surface of the main road along the western shore of the dead sea was opened by a passing bus repeated infilling and collapse of these holes indicated the extent of this ongoing process and the significance of this developing hazard since then sinkholes have developed in other areas including qalia ein samar ein gedi and mineral beach

sinkhole hazards along the eastern dead sea shoreline area jordan a geological and geotechnical consideration for the last four decades the level of the dead sea has been subjected to continual variation which among other important factors has led to the occurrence of much subsidence and many sinkholes in the southern dead sea area sinkhole activities occurred repetitively and were observed in open farms across roads near dwellings and near an existing factory thus causing a serious threat to the locals and farmers of the area and their properties this paper presents the main results from detailed geological and geotechnical studies of this area aerial photo interpretation and borehole drilling aided these studies parallel geophysical investigations vertical electrical sounding and seismic refraction and hydrological and hydrogeological studies were made by others in the same area to also investigate this phenomenon it was found that sinkholes are aligned to and follow old water channels and are concentrated parallel to the recent shoreline of the dead sea the development of subsurface cavities is associated mainly with the variation in the level of the dead sea over the four past decades the presence of regional salt intrusion under the surface of salt beds the fluctuation of the water table and continuous dissolution and the active tectonism of the area moreover this work showed that the area is still under active sinkhole hazards and other parts of the area will be inevitably affected by sinkholes in the future no practical engineering solution to this problem is feasible

dynamic dissolution of halite rock during flow of diluted saline solutions 1 the dynamic dissolution pattern of halite salt rocks taken from coreholes near the dead sea was studied in laboratory scale experiments when unsaturated solution with respect to halite flowed through salt cores dissolution developed along preferential flow pathways in a channel structure the channel structure was related to the salt s properties and internal heterogeneities flow velocity and impact of gravity preferential dissolution pathways developed in areas of minimum resistance to flow such as large pore networks and cracks nevertheless in many cases no structural heterogeneity was observed along the dissolution channels prior to the experiments the initial formation of channels took place above a critical flow velocity below this threshold dissolution developed as a slowly propagating front in these cases salt re precipitation resulted in clogging and cessation of flow through a few of the salt cores solution density was found to be important as evidenced by the fact that more channels developed upward than downward due to gravitational fractionation the development of dissolution channels could have very important implications for the overall permeability of the salt layer in general and the use of salt formations for industrial waste storage and the development of sinkholes along the dead sea shore in particular

structural evolution and sequence formation offshore south gabon during the tertiary abstract the present investigation of the tertiary succession offshore south gabon is based on seismic surveys of 1985 1989 vintage and wells covering the southern part of gabonese waters in general the tertiary basin off south gabon evolved during two structural stages during the paleocene and early middle eocene a trough like basin subsided slowly towards the west during this period there was a cyclic development of the succession which consists of up to four sequences mostly bounded by type 2 sequence boundaries the sequential changes were induced by eustatic sea level changes this pattern changed during the neogene when the evolution was characterized by continental crustal flexuring in early middle miocene times this resulted in strong subsidence of the western part of the basin and uplift of the eastern part consequently the eastern part was exposed to strong erosion and a thick middle miocene succession was deposited west of the shelf approximately the present day shelf especially on the slope the clinoformal and lens shaped middle late miocene succession which consists of four sequences bounded by type 1 sequence boundaries has been controlled by eustatic changes in sea level in addition to the overall subsidence pattern salt tectonics has modified the external and internal architecture of the sequences on a local scale canyon formation in connection with slumping results in the establishment of well developed fan systems on the lower part of the slope and on the basin floor area