spatial distribution morphometry and activity of la puebla de alfinden sinkhole field in the ebro river valley ne spain applied aspects for hazard zonation a highly active collapse sinkhole field in the evaporitic mantled karst of the ebro river valley is studied ne spain the subsidence is controlled by a nw se trending joint system and accelerated by the discharge of waste water from a nearby industrial state the morphometry spatial distribution and temporal evolution of the sinkholes have been analysed the volume of the sinkholes yields a minimum estimate of average lowering of the surface by collapse subsidence of 46 cm the clustering of the sinkholes and the tendency to form elongated uvalas and linear belts in a nw se direction have a predictive utility and allow the establishment of criteria for a hazard zonation with the precipitation record supplied by a pluviograph and periodic cartographic and photographic surveys the influence of heavy rainfall events on the triggering of collapses has been studied

characterization of karst hazards from the perspective of the doline triangle using gpr examples from central ebro basin spain ground penetrating radar gpr is a widespread technique to locate and characterise karst hazards cavities and paleocollapses in this paper we show that the internal structure of sediments obtained from gpr surveys can also be used as an indicator of active karst processes a classification of karst hazard problems by means of gpr in the gpr doline triangle is proposed with three end members cavities evidences of subsidence and paleocollapses these end members show particular signatures in the gpr profiles the field examples shown in this paper indicate that gpr survey is a geophysical technique that offers a very high resolution and provides structural and sedimentological information of the subsoil the use of grid maps elaborated from gpr data is an efficient way to determine anomalous sectors lateral changes of electromagnetic properties different reflectivity and qualitative penetration depth variations or velocity wave propagation changes their relationships with the structural features obtained from gpr profiles on lap geometries zones with depressed reflectors folded reflectors or laterally abrupt structural limits can be used as indicators of karstic processes

a generalized genetic framework for the development of sinkholes and karst in florida u s a karst topography in florida is developed on the tertiary limestones of the floridan aquifer post depositional diagenesis and solution have made these limestones highly permeable t ca 50 000 m2 d zones of megaporosity have formed at unconformities and dissolution has enlarged joints and fractures erosion of the overlying clastic miocene hawthorn group strata on one flank of a structural arch has exposed the limestone the elevated edge of the hawthorn cover forms the cody scarp ubiquitous solution pipes have previously formed at joint intersections and are now filled downwashing of the fill deeper into solution cavities in the limestone and subsidence of the overlying unconsolidated sediments causes surface collapse a subsidence doline or sinkhole this process may penetrate up to 60 m of the semi consolidated hawthorn cover as occurred when the winter park sinkhole developed dense clusters of solution pipes may have formed cenotes which are now found on the exposed limestone terrain

degradation processes along the new northeastern shores of the dead sea since about 6 decades the dead sea shore has been retreating exposing herewith shore sediments consisting of alluvial deposits underlain by muds enhanced erosional processes by flood and base flows as a result of increasing gradients of slopes have incised deep gorges in the black mud sediments which have resulted in land collapses landslides and shrinking fractures erosion has exposed structures resembling seismites and subaquatic fossil slidings in this article the degrading geology of the northeastern shore of the dead sea is described and the underlying geo mechanical mineralogical and chemical properties of the black mud sediments composed of silt and clay partly covered by gravel and sand are evaluated attention is also paid to the impacts of the degrading geology on the infrastructure of the area and remediation measures are recommended

gis based assessment of risk due to salt mining activities at tuzla bosnia and herzegovina ground subsidence triggered by salt mining from deposits located beneath the city of tuzla bosnia and herzegovina is one of the major dangers acting on a very densely urbanized area since 1950 when the salt deposit exploitation by means of boreholes began as demonstrated in this paper subsidence induced several hazard factors such as severe ground deformations the arising of deep and superficial fractures and a very fast water table rise connected with the brine extraction now affecting several districts the above mentioned factors have been quantified by the use of geomatic methodologies including field surveys and analysis of geographical data in order to estimate the historical sinking rates authors processed the large and never before processed amount of topographical data collected during two periods from 1956 to 1991 and from 1992 to 2003 with only poor data collected afterward traditional surveys were completely and definitively stopped the analysis reveals a cumulative subsidence as high as 12 m during the whole period causing damage to buildings and infrastructures within an area that includes a large portion of the historical town at present almost entirely destroyed modern sinking rates have been monitored with static gps whereas the presence of superficial fractures monitored with kinematic gps factors related to the presence of deep fractures and water table rise have been evaluated by curvature analysis techniques and piezometric data respectively finally hazard factors have been combined in a risk map using the gis geographical information system map algebra capabilities and a simple multicriteria decision analysis mda in order to do that a vulnerability map has been derived on the basis of information reported on a couple of recently sensed high resolution satellite imageries the final risk arisen from the combination of single hazard factors and vulnerability map highlights critical scenarios and unsuspected threatening that are under consideration by the local decision makers and urban planners in particular as highlighted in the final risk map the present day water table rise triggered by the decrease in brine pumping is seriously posing a threat to a portion of the city which is not the most involved in ground deformations

monitoring ground subsidence induced by salt mining in the city of tuzla bosnia and herzegovina salt mining induced ground subsidence is a major hazard in the city of tuzla northeastern sector of bosnia and herzegovina and its surroundings since 1950 when solution mining of salt deposits by boreholes began an analysis of the large and never before processed amount of topographical data collected during two periods from 1956 to the balkan war and from 1992 to 2003 has been made the analysis reveals a cumulative subsidence as high as 12 m during the whole period causing damage to buildings and infrastructures within an area that includes a large portion of the historical town human induced subsidence with rates up to 40 cm year in the most developed area has been investigated to recognize the areas affected by the sinking phenomenon and to produce a subsidence hazard the time series of topographical observations have been enlarged by conducting new surveys in the urban area by modern space geodesy methodologies such as static relative gps global positioning system and high resolution satellite imageries the gps monitoring started in 2004 and detected a decrease in the subsidence rates to 20 cm year related to the reduction of salt exploitation there is close correlation between the average subsidence rate and the annual amount of salt extracted

a case of man induced ground subsidence and building settlement related to karstified gypsum oviedo nw spain this paper presents the research carried out to shed light on a sudden settlement and its consequences that occurred in the city of oviedo ground subsidence in the ventanielles area led to severe damage and the subsequent demolition of two buildings with 362 flats resulting in losses of 18 million euros the investigation allowed the identification of a buried sinkhole filled with up to 13 m of fluvial sediments linked to the dissolution of a paleogene gypsum unit with a maximum thickness of 18 m and containing metre sized cavities the triggering process that reactivated the paleosinkhole was found to be the pumping of water from a confined aquifer related to excavation work during the construction of a nearby underground parking lot this extraction modified the natural hydrological regime the compaction and migration of alluvial sand towards the karstic cavities were the main subsidence mechanisms responsible for the structural damage aggravated by the poor quality of the buildings and the geotechnical behaviour of the supporting ground

the influence of urbanization of sinkhole development in central pennsylvania the karsted limestone valleys of central pennsylvania contain two populations of sinkholes solution sinkholes occur in the champlainian limestone units along the margins of the valleys solution sinkholes are permanent parts of the landscape and although a nuisance to construction do not present other problems the second population is the suffosional or soil piping sinkholes these occur on all carbonate rock units including the beekmantown and gatesburg dolomites that comprise the two principal carbonate aquifers in the valley suffosional sinkholes are the principal land use hazard suffosional sinkholes are transient phonomena they occur naturally but are exacerbated by runoff modifications that accompany urbanization suffosional sinkholes are typically 1 5 2 5 m in diameter depending on soil thickness and soil type the vertical transport of soil to form the void space and soil arch that are the precursors to sinkhole collapse is through solutionally widened fractures and cross joints and less often through large vertical openings in the bedrock the limited solution development on the dolomite bedrock combined with soil thickness seldom greater than 2 m limits the size of the sinkholes all aspects of suffosional sinkhole development are shallow processes transport piping void and arch formation and subsequent collapse take place usually less than 10 m below the land surface factors exacerbating sinkhole development include pavement street and roof runoff which accelerates soil transport such seemingly minor activities as replacing high grass and brush with mowed grass is observed to accelerate sinkhole development dewatering of the aquifer is not a major factor in this region

subsidence rates and urban damages in alluvial dolines of the central ebro basin ne spain in the central ebro basin alluvial dolines develop on quaternary materials overlying neogene evaporites this process is very active analysing aerial photographs of different years important differences can be observed since the 1970s when the urbanisation of the area took place karst processes have damaged many buildings and infrastructures from the dates of construction and the repair of a number of buildings and pavements we calculate subsidence rates 12 120 mm year moreover we decided to monitor for around 4 years three dolines developed on urban areas to determine their subsidence behaviour a water level device with an error of 2 3 mm was utilised for this purpose the subsidence rates so obtained are 64 5 39 and 21 mm year which fit with the previous data from repaired zones

space time distribution of ancient and active alluvial karst subsidence examples from the central ebro basin spain space and time variations of alluvial karst subsidence in the central ebro basin are analysed in trenches paleodolines aerial photographs historical dolines and field surveys present day active dolines the measured subsidence rates as well as a comparison between densities of paleodolines computed in randomly selected scan lines and density of active dolines computed in maps suggest that present day subsidence in favourable areas is more intense than that of pleistocene times according to diachronic maps drawn from a different aerial photographs taken after 1946 and b field surveys on deformations in urbanized areas subsidence behaved as a nearly steady process while the whole area was used for agriculture in contrast rapid changes through periods of several tens of years have occurred in urbanized areas in which dolines expand their boundaries through small marginal collapses shifting sharply their sinking centres to neighbouring sites these rapid changes do not have an equivalent in observed paleodolines

gypsum karstification in the middle miocene fatha formation mosul area northern iraq abstract karstified middle miocene sediments are widely exposed in northern iraq particularly in the area surrounding the city of mosul the unit is dominated by gypsum and exposed in thirteen anticlinal structures within the investigated area of about 1600 square kilometers synclines though containing the same sequence are not karstified due to a quaternary cover karst features were located from air photos over 4000 were recorded the smallest detectable being two meters in diameter the majority are sinkholes dolines developed in gypsum and manifested in the overlying collapsing limestone they are singular in lines or clusters shafts and karren are fewer in number and are usually developed in uncovered gypsum sinkholes are visibly located along fractures and at fracture intersections over gently inclined limestone beds overlying the gypsum two karst systems were identified an active and recent system characteristic of all the anticlinal structures and an older pleistocene fossil karst system characteristic of alan ishkaft albu saif and hammam structures the fossil karst system is preserved on remnant elevated old land surfaces and produces characteristic tight undulations in the limestone due to collapse inwards in sinkholes and elongated tunnels formed along a series of sinkholes the fracture study of anticlinal structures reveals that the mean fracture density per area ranges between 4 and 8 km km 2 and shows a unimodal character for most of the structures however the distribution of karst in relation to fractures is bimodal for at least half of the structures with mean values ranging from 4 5 to 11 km km 2 the fractures in the anticlines are thought to have formed due to folding but some are associated with major lineaments cross cutting the structures which is reflected in the bimodality and the crude unimodal fracture karst distribution karst features are related to the general fracture pattern but are more localized in densely fractured areas karst areas were also found to correlate with lower slope gradient and lower drainage density

combining geophysical data sets to study the dynamics of shallow evaporites in urban environments application to hamburg germany summary shallowly situated evaporites in built up areas are of relevance for urban and cultural development and hydrological regulation the hazard of sinkholes subrosion depressions and gypsum karst is often difficult to evaluate and may quickly change with anthropogenic influence the geophysical exploration of evaporites in metropolitan areas is often not feasible with active industrial techniques we collect and combine different passive geophysical data as microgravity ambient vibrations deformation and hydrological information to study the roof morphology of shallow evaporites beneath hamburg northern germany the application of a novel gravity inversion technique leads to a 3 d depth model of the salt diapir under study we compare the gravity based depth model to pseudo depths from h v measurements and depth estimates from small scale seismological array data while the general range and trend of the diapir roof is consistent a few anomalous regions are identified where h v pseudo depths indicate shallower structures not observed in gravity or array data these are interpreted by shallow residual caprock floaters and zones of increased porosity the shallow salt structure clearly correlates with a relative subsidence in the order of 2 mm yr 1 the combined interpretation of roof morphology yearly subsidence rates chemical analyses of groundwater and of hydraulic head in aquifers indicates that the salt diapir beneath hamburg is subject to significant ongoing dissolution that may possibly affect subrosion depressions sinkhole distribution and land usage the combined analysis of passive geophysical data may be exemplary for the study of shallow evaporites beneath other urban areas

the origin typology spatial distribution and detrimental effects of the sinkholes developed in the alluvial evaporite karst of the ebro river valley downstream of zaragoza city ne spain three types of sinkhole have been mapped in a 50 km2 stretch of the ebro river valley downstream of zaragoza large collapse sinkholes large shallow subsidence depressions and small cover collapse sinkholes the sinkholes relate to the karstification of evaporitic bedrock that wedges out abruptly downstream giving way to a shale substratum twenty three collapse sinkholes up to 50 m in diameter by 6 m deep and commonly hosting saline ponds have been identified in the floodplain they have been attributed to the upward stoping of dissolutional cavities formed within the evaporitic bedrock by rising groundwater flows twenty four large shallow subsidence depressions were mapped in the floodplain these may reach 850 m in length and were formed by structurally controlled interstratal karstification of soluble beds halite or glauberite and gypsum by rising groundwater flow and the progressive settlement of the overlying bedrock and overburden sediments a total of 447 small cover collapse or dropout sinkholes have been recognized in a perched alluvial level along the southern margin of the valley these sinkholes result from the upward propagation of voids through the alluvial mantle caused by the downward migration of detrital sediments into dissolutional voids the majority of these sinkholes commonly 1 5 2 m in diameter are induced by human activities over the karstic bedrock there is a significant increase in sinkhole density downstream this is interpreted as being a result of the evaporitic bedrock wedging out and the convergence of the groundwater flow lines in the karstic aquifer the collapse sinkholes in this area locally with a probability of occurrence higher than 140 sinkholes km2 year cause substantial damage to the linear infrastructures buildings and agriculture and they might eventually cause the loss of human lives copyright 2006 john wiley sons ltd

stratigraphic architecture of alluvial aeolian systems developed on active karst terrains an early pleistocene example from the ebro basin ne spain abstract during the early pleistocene fluvial alluvial and aeolian depositional systems interacted in the central ebro basin spain constructing wide alluvial plains over a neogene evaporite substratum fluvial sediments mainly longitudinal gravel bars and channels are interdigitated with gravel mass flow and distal mudflat deposits aeolian sedimentation is registered as aeolian dunes and sand sheets episodes of fluvial deposition alternated with periods of alluvial fan progradation and aeolian deposition these changes are related to climate driven water availability stratigraphic units and deformation structures show synsedimentary karstification of the evaporite substratum that although karst was not restricted to any particular climate scenario was probably favoured during periods of high water availability karstification conditioned the development of local sedimentary depocentres which in turn influenced the distribution of sedimentary subenvironments as well as the accumulation and preservation of aeolian dunes and lacustrine palustrine deposits stratigraphic architecture shows that thickening of the series due to karst subsidence did not occur homogeneously but was controlled by diachronous subsidence resulting in numerous angular unconformities in subsiding karst areas transport capacity was reduced and sediment preservation increased

large scale karst subsidence and accelerated fluvial aggradation during mis6 in ne spain climatic and paleohydrological implications abstract fluvial systems crossing evaporitic bedrock are commonly affected by karstic subsidence which may result in river adjustments recorded by anomalous alluvial thickening a remarkable study case is the gallego river at the central ebro basin ne spain where dissolution of evaporite bedrock gave rise to a subsidence induced depositional basin 30 km long by 8 km wide infilled with alluvial sediments in excess of 110 m in thickness a detailed morpho sedimentary analysis of alluvial deposits supported with optically stimulated luminescence dating has revealed that paleokarst subsidence and accelerated fluvial aggradation occurred during discrete time periods the most recent one being at 140 155 kyr end of mis 6 subsequent alluvial terrace formation occurred at 110 kyr 63 48 kyr and 17 kyr linked to fluvio glacial activity at the pyrenean headwaters large scale bedrock dissolution and associated alluviation appear to be sensitive to 1 long lasting periods of glacial outwash discharges 2 high effective runoff from the extensive valley slopes and 3 increased surface groundwater exchange and groundwater circulation the last large scale subsidence episode 140 155 kyr correlates with hydrological proxies reflecting a prolonged 141 149 kyr salinity drop in the western mediterranean previously interpreted as linked to a heinrich event but which may instead represent an anomalous period of enhanced river discharge fed by extensively glaciated mountains

doline probability map using logistic regression and gis technology in the central ebro basin spain in the surroundings of zaragoza karstification processes are especially intense in covered karst areas where fluvial terraces lie directly on tertiary evaporites since the beginning of quaternary these processes have lead to the development of collapse and subsidence dolines with a wide range of sizes which have significant economic impacts to reduce economic impact and increase safety a regional analysis of this phenomenon is needed for spatial management therefore a probability map of dolines was developed using logistic regression and geographic information system gis techniques this paper covers the selection of input data manipulation of data using the gis technology and the use of logistic regression to generate a doline probability map the primary variable in the doline development in this area is geomorphology represented by the location of endorheic areas and different terrace levels secondary variables are the presence of irrigation and the water table gradient

geomorphological geochemical and geo environmental aspects of karstification in the urban areas of kerman city southeastern iran kerman city has a semiarid arid climate with an average annual precipitation of about 158 mm the area is underlain by soluble subsoil and alluvial deposits overlying highly fractured cretaceous limestones geo environmental studies indicate that both paleokarst and active karst features are developed in the area the paleokarsts were developed in the upper cretaceous limestone during the cold humid periods of post cretaceous and probably early quaternary time and include honeycombs solution flutes rillenkarren caverns and solution collapse dolines active karst landforms occur by combined piping induced and limestone solution at depth in subsoils and alluvial deposits and bajada that overly potent karstic limestones and cover subsidence sinkholes and subjacent alluvial karst collapse dolines many factors such as soluble compounds salt and gypsum desiccation cracks and qanat dug water wells could contribute to the development of karstic landforms the most immediate cause for active karst landforms is considered to be the drawdown of the water table in the area there is an increasing demand for groundwater consumption to irrigate pistachio fields excessive pumping of the groundwater lowers the water table about 80 cm per year this rate of drawdown accelerates land subsidence about 6 cm per year creates circular patterns of fractures in the ground and in buildings disrupts agricultural work and urbanization projects and tilts foundations these geohazards indicate that ground sinking and karstification are in progress in the alluvial deposits and underlying limestones the disturbance and expense caused by the geohazards could be mitigated by the application of overhead sprinkler irrigation for pistachio fields or by planting less thirsty plants

array invariant based source localization in shallow water using a sparse vertical array the array invariant proposed for robust source localization in shallow water exploits the beam time migration of broadband signals the approach requires minimal knowledge of the environment but involves plane wave beamforming using a short aperture vertical array in stratified acoustic waveguides in this paper the array invariant approach is extended to a large aperture vertical array that is sparse with significant variation of the sound speed across the aperture for conventional beamforming the extension is feasible because the array invariant in shallow water utilizes surface bottom reflected arrivals that behave like those in ideal waveguides robust source range estimation is demonstrated using data from a 16 element 56 m long vertical array at various ranges 1 5 3 5 km from a broadband source 0 5 2 khz in approximately 100 m deep shallow water

evaluating and comparing methods of sinkhole susceptibility mapping in the ebro valley evaporite karst ne spain abstract multiple sinkhole susceptibility models have been generated in three study areas of the ebro valley evaporite karst ne spain applying different methods nearest neighbour distance sinkhole density heuristic scoring system and probabilistic analysis for each sinkhole type separately cover collapse sinkholes cover and bedrock collapse sinkholes and cover and bedrock sagging sinkholes the quantitative and independent evaluation of the predictive capability of the models reveals that 1 the most reliable susceptibility models are those derived from the nearest neighbour distance and sinkhole density these models can be generated in a simple and rapid way from detailed geomorphological maps 2 the reliability of the nearest neighbour distance and density models is conditioned by the degree of clustering of the sinkholes consequently the karst areas in which sinkholes show a higher clustering are a priori more favourable for predicting new occurrences 3 the predictive capability of the best models obtained in this research is significantly higher 12 5 82 5 than that of the heuristic sinkhole susceptibility model incorporated into the general urban plan for the municipality of zaragoza although the probabilistic approach provides lower quality results than the methods based on sinkhole proximity and density it helps to identify the most significant factors and select the most effective mitigation strategies and may be applied to model susceptibility in different future scenarios

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

geological and environmental implications of the evaporite karst in spain in spain evaporite outcrops cover approximately 7 of the total area of the country most of the evaporitic formations are made up of ca sulfates gypsum anhydrite or ca sulfates and halite certain paleogene marine evaporites also contain k mg chlorides and some tertiary continental formations bear substantial amounts of na sulfates in the subsurface glauberite and thenardite mesozoic evaporitic formations commonly wedge out towards the ground surface passing into condensed sequences and dissolution collapse breccias some of these highly porous breccias constitute major regional aquifers in several areas interstratal karstification of the evaporites has given rise to gravitational deformations such as basin structures monoclines and collapse structures covering several square kilometers that record a cumulative subsidence in excess of 200 m teruel and calatayud grabens a widespread consequence of evaporite dissolution processes in spain is the hydrochemical degradation of surface waters some of the largest and most outstanding lake systems from an environmental perspective occur in karstic depressions developed in evaporitic formations fuente de piedra gallocanta bujaraloz and banolas lakes sinkhole activity is a major geohazard in several evaporite karst areas the sinkhole risk has a particularly high impact in sectors where tertiary evaporites are overlain by quaternary alluvial aquifers calatayud zaragoza and madrid areas some of the detrimental effects of subsidence include severe damage to historical monuments calatayud the demolition of a whole village puilatos or the derailment of a freight train zaragoza area the deepest gypsum caves are found in triassic diapiric structures el sumidor cave 210 m deep and the longest ones are developed in horizontally lying neogene sequences sorbas caves and estremera maze cave the cardona diapir hosts salt caves up to 4 300 m long whose genesis is related to flooding of mine galleries caused by the interception of a phreatic conduit the main anthropogenic impacts on the endokarstic systems are related to the disposal of wastewaters and the destruction of caves by quarrying the fluvial valleys that cross tertiary evaporitic outcrops commonly show peculiar geological characteristics related to dissolution induced synsedimentary subsidence phenomena 1 thickened alluvium filling dissolution basins up to several tens of kilometers long and more than 100 m deep the largest thickenings are found in areas where the bedrock contains halite and glauberite 2 superimposed alluvial units locally bounded by angular unconformities 3 abundant deformational structures and paleosinkholes related to the rockhead and or interstratal karstification of the substratum these fluvial valleys typically are flanked by a prominent gypsum escarpment rock falls favored by the dissolutional enlargement of joints derived from these scarps are the type of mass movement which has caused the highest number of casualties in spain

environmental and engineering problems of karst geology in china karst terrane is generally regarded as a fragile and vulnerable environment its underground drainage system can aggrevate both drought and flood problems the lack of filtration in an underground conduit makes waste disposal more difficult and the lack of soil cover in bare karstland can enhance deforestation moreover karst terranes are quite often haunted by a series of engineering problems such as water gushing into mines or transportation tunnels leakage from reservoirs and failure of building foundations in china there are more than 200 cases of karst collapse which include many thousands of individual collapse points some of these are paleo and natural collapses but most of them are modern collapses induced by human activities and they have caused serious damage many factors such as geologic structure overburden thickness and character lithologic features of karstified rock and intensity of karstification are related to development and distribution of modern collapses however china s karst is mainly developed in pre triassic old phase hard compact carbonate rock consequently most modern collapses have occurred only in the overlying soil so it is understandable that the fluctuation of the water table in the underlying karstified strata plays an important role in the process of collapse nevertheless there are different explanations as to how the groundwater activities can induce collapse

subsidence hazard avoidance based on geomorphological mapping in the ebro river valley mantled evaporite karst terrain ne spain in the valley of the ebro river to the southeast of the city of zaragoza ne spain the dissolution of evaporite sediments gypsum halite and na sulphates which underlie alluvial deposits gives rise to numerous sinkholes these sinkholes are a potential hazard to human safety particularly where they develop in a catastrophic way even slow developing sinkholes are problematic as they damage urban and agricultural infrastructure necessitating costly repairs and vigilant maintenance to assist in developing avoidance strategies for these hazards the factors controlling sinkhole occurrence have been assessed using geomorphological maps produced from aerial photographs for 1956 and 1981 important controls on sinkhole development are found to include underlying geological structure manifest in preferred orientations of sinkholes on the azimuths n130 150e and n30 40e and the presence of glauberite in the groundwater flow path which apparently promotes accelerated gypsum dissolution perhaps surprisingly alluvium thickness does not appear to significantly correlate with the density of sinkholes on the floodplain in this area the maps for 1956 and 1981 reveal that both human activity and natural processes can serve to obscure the true density of sinkhole development for instance a large number of sinkholes which were conspicuous in 1956 have since been back filled by farmers in the most fluvially active zone of the ebro valley the meander belt the relatively low density of sinkholes compared with adjoining zones suggests that subsidence is being masked by morpho sedimentary dynamic processes aggradation and erosion careful geomorphological mapping for different time periods yields a much more accurate impression of the frequency of sinkhole development than would be gained from surveying currently visible sinkholes in the area of interest

investigation of sinkholes spatial distribution using the weights of evidence method and gis in the vicinity of karapinar konya turkey abstract there are many sinkholes 182 in the vicinity of karapinar approximately 20 large sinkholes 10 m in diameter were formed within the obruk plateau between 1970 and 2012 the formation of sinkholes is the most important geological hazard in the study area because they can damage engineering structures settlements agricultural areas and eventually be a source of casualties to date no study has been conducted on the distribution of sinkholes in this region in this study the spatial distribution of the sinkholes and the factors controlling sinkhole development were studied through the use of geographical information systems using a sinkhole inventory and a spatial database containing information on the topography geology hydrogeology and land use initially 182 sinkholes were identified in the area by examining the digital elevation model produced for this study the sinkholes were verified in the field thirty two factor maps were produced to investigate their relationship with sinkholes using the weights of evidence method the sinkholes are mainly related to dissolution of the neogene age lacustrine insuyu formation consisting of limestone and clayey limestone sinkhole frequency increases in the vicinity of drainages 2000 3000 m and faults

interacting tectonic faulting karst subsidence diapirism and continental sedimentation in pleistocene deposits of the central ebro basin spain during early as proposed by the international commission on stratigraphy pleistocene times interacting fluvial and aeolian processes constructed wide alluvial plains over an evaporite dominated miocene substratum in the central ebro basin an exceptional site where these deposits show faults folds diapirs karst structures and unconformities has been studied in detail analysis of particular structures demonstrates the interaction by that time of tectonic faulting diapirism karstification and sedimentation in an area where deformation was traditionally linked to the presence of underlying evaporites without proposing any precise mechanism multiple approaches sedimentology structural geology and geophysics have been used in order to discriminate the origin of each type of structure as well as to understand the interaction between different processes numerous normal faults and fractures of variable size are consistent with the regional stress field pleistocene deposits are pierced by diapirs of miocene evaporites and disrupted by karst structures with different geometries tubular funnel and vault both partially controlled by tectonics the example described is proposed as an analogue model that could successfully illustrate evolution patterns of basins of potential interest for petroleum geology where similar processes have actuated resulting in complex stratigraphical architectures

a multidisciplinary approach in sinkhole analysis the quinis village case study ne italy abstract during the last recent years in quinis a small village sited in the alta val tagliamento valley friuli venezia giulia region ne italy the inhabitants faced with instability phenomena related to the presence of soluble rocks in the subsurface the evaporite bedrock is mainly mantled in fact by high thickness deposit this paper explains the methodological approach that we used to identify the instabilities in a very complex geo structural environment where the urbanization limits the applicability of several investigation techniques different methods were used to define the bedrock morphology to characterize the mantling deposits and to identify the processes behind what emerged from the study is a mandatory multidisciplinary approach to characterize the subsoil because each technique is not able individually to take to a unique result the data collected allowed to draft a geo hydrogeological conceptual model of the quinis village the lessons learned even if with some site specific dependency demonstrate the importance of broad spectrum investigations which are essential to understand the subsurface characteristics avoiding relevant socio economic impact and supporting an adequate future territorial planning

sedimentary record of pleistocene paleodoline evolution in the ebro basin ne spain abstract pleistocene fluvial deposits of the ebro river in ne spain are widely affected by faults fractures and tilting of beds based on the lithological geometrical and textural features of these deposits seven architectural elements have been differentiated gravel bars gb gravel filled channels ch sheets and channel fill sands sb are the most common elements and together with less frequent overbank fines ff characterize a gravel dominated braided fluvial system gravel lobes gl that draw progressive unconformities and are laterally related to u shaped or basin form mud deposits sediment gravity flow deposits sg and sands with slumps and convolute bedding sgs are not typical architectural elements of braided fluvial environments and they are interpreted in this work as related to syn sedimentary deformation our research proves that deformation is due to dissolution of the underlying tertiary evaporites with genesis of dolines the development of these karst structures involved both subsidence and sudden collapses that affected previous fluvial sediments small depressions dolines generated that were progressively filled by syn sedimentary deformed detrital deposits a model for the evolution of the doline fills is purposed that envisages several stages 1 gravitational processes caused remobilisation of previous fluvial gravels that were dragged to the created depression 2 flooding of the depression and development of a backswamp area that was progressively filled by fine sediments and gravel lobes as a consequence of the overflow of nearby channels 3 gravel lobes draw progressive unconformities revealing several subsidence episodes related to dissolution dragging and compaction 4 non deformed fluvial facies at the top of the series mark the end of the karstification influence osl optically stimulated luminiscence ages the first from the terraces of the ebro river demonstrate that karst has developed in this area at least since the late pleistocene and that the dolines have been filled in throughout several thousand years this large span time of doline evolution without anthropogenic influence should be considered for a better planning and management in hazardous areas

assessing karst hazards in urbanized areas case study and methodological considerations in the mantle karst from zaragoza city ne spain abstract mantle karst environments can be analyzed by means of historical geophysical and geomechanical approaches with the objectives of avoiding urban development in hazardous areas or to establish guidelines for foundation design nevertheless geophysical and geomorphological techniques can show complexities in interpretation in urban domains in order to analyze their limits and resolutions historical approaches geophysical surveys and field inspection are here combined with the analysis of building and construction problems in urbanized sectors the particular case study presented is a sinkhole affecting three different domains an agricultural area an uncultivated plot and an urbanized zone where surficial karst evidences affecting streets roads and buildings are observed the results obtained permit to analyze the noises from urban environments for both magnetic and electromagnetic multifrequency techniques and the limitations of ground penetrating radar gpr survey in agricultural areas with clayey soils and subhorizontal conductive layers the comparison and evaluation of different approaches and geophysical techniques in the three domains permit to define an efficient routine in order to characterize surficial evidences structural changes in underground materials and changes in their geophysical characteristics

curvature analysis as a tool for subsidence related risk zones identification in the city of tuzla bih abstract shallow miocene salt deposits located below the city of tuzla bih have been exploited during the last 60 years by means of wells extracting salt saturated groundwater brines the massive extraction activities have led to severe subsidence accommodated by collapse and strain localization surface topography and geomorphology have been influenced and modified by several faults and fractures a series of sequential topographical survey data collected during the last 50 years have been used to obtain the total subsidence envelope surface in order to analyze the salt dissolution related morphological development of the tuzla topography and to identify the location of faults and fractures in the deformed area we applied curvature analysis to the subsidence surface by means of two different analytical methods the directional two dimensional curvature and the analytic gaussian curvature the comparison of the curvature maps with those of surface fractures visible in the area shows a good spatial agreement between the directional curvature and fracture intensity whereas the subsurface normal faults are more evident in the gaussian curvature maps

geomorphology of the tertiary gypsum formations in the ebro depression spain abstract this paper reviews the current knowledge of the mainly karstic geomorphological features developed in the evaporitic formations of the ebro depression northern spain special emphasis is given to the recently published and unpublished scientific advances the gypsum formations of tertiary age have an extensive outcrop area within the ebro depression here their morphogenesis is controlled mainly by processes of surface and subsurface dissolution acting on the gypsum outstanding landforms in the gypsum terrain include saline lakes developed in flat bottom dolines saladas other characteristic morphologies include karren and gypsum domes which occur on a decimetre scale where the gypsum is covered by quaternary alluvial deposits the karstification processes are especially intense and cause subsidence phenomena karstic subsidence affects stream terraces mantled pediments and infilled valleys which in the region are called vales dissolution induced synsedimentary subsidence has produced interesting geological features which include significant thickening and deformation of the alluvial deposits in contrast to the rapid removal of gypsum by dissolution the amount of gypsum removed by erosion is low water erosion studies carried out on gypsiferous slopes of the ebro depression indicate that the sediment yield ranges from 0 59 to 7 82 t ha year this low yield results from the high infiltration capacity of the soils subsidence caused by gypsum dissolution has important socio economic consequences in the ebro depression the active alluvial karstification of the gypsum causes numerous sinkholes that are harmful to linear structures roads railway lines irrigation channels buildings and agricultural land unforeseen catastrophic subsidence also puts human lives at risk the benefits of such terrains include thickened alluvial deposits which act as valuable water reservoirs and which form excellent sources of aggregates fluvial valleys in this gypsiferous terrain commonly show an asymmetrical geometry with prominent gypsum scarps at one side these gypsum scarps are affected by numerous landslides these slope movements are hazardous may dam rivers and cause flooding of the alluvial plains

karst subsidence as a control on the accumulation and preservation of aeolian deposits a pleistocene example from a proglacial outwash setting ebro basin spain meltwater flows emanating from the pyrenees during the pleistocene constructed a braided outwash plain in the ebro basin and led to the karstification of the neogene gypsum bedrock synsedimentary evaporite dissolution locally increased subsidence rates and generated dolines and collapses that enabled the accumulation and preservation of outwash gravels and associated windblown deposits that were protected from erosion by later meltwater flows in these localized depocentres maximum rates of wind deceleration resulted from airflow expansion enabling the accumulation of cross stratified sets of aeolian strata climbing at steep angles and thereby preserving up to 5 m thick sets the outwash plain was characterized by longitudinal and transverse fluvial gravel bars channels and windblown facies organized into aeolian sand sheets transverse and complex aeolian dunes and loess accumulations flat lying aeolian deposits merge laterally to partly deformed aeolian deposits encased in dolines and collapses synsedimentary evaporite dissolution caused gravels and aeolian sand deposits to subside such that formerly near horizontal strata became inclined and generated multiple internal angular unconformities during episodes when the wind was undersaturated with respect to its potential sand transporting capacity deflation occurred over the outwash plain and coarse grained lags with ventifacts developed subsequent high energy flows episodically reached the aeolian dune field leading to dune destruction and the generation of hyperconcentrated flow deposits composed in part of reworked aeolian sands lacustrine deposits in the distal part of the outwash plain preserve rhythmically laminated lutites and associated gilbert type gravel deltas which developed when fluvial streams reached proglacial lakes this study documents the first evidence of an extensive pleistocene proglacial aeolian dune field located in the ebro basin 41 50 n south of what has hitherto been considered to be the southern boundary of pleistocene aeolian deposits in europe a non conventional mechanism evaporite karst related subsidence for the preservation of aeolian sands in the stratigraphic record is proposed

sinkholes in the salt bearing evaporite karst of the ebro river valley upstream of zaragoza city ne spain geomorphological mapping and analysis as a basis for risk management abstract a detailed sinkhole map has been produced in a stretch of the ebro valley 40 8 km2 including the western sector of zaragoza city ne spain during the last few decades around 70 of the original sinkhole area has been filled with anthropogenic sediments causing the disappearance of 137 ha of wetlands the interstratal karstification of salts halite and glauberite and a wnw ese trending joint set have played a major control in the development of sinkholes three morphometric types of sinkholes have been differentiated each attributed to a specific subsidence mechanism inferred from the paleosinkholes exposed in the surrounding of zaragoza city sagging of bedrock and cover collapse of bedrock and cover and collapse of cover material related to the downward migration of particles through dissolutional conduits each type of sinkhole is characterised by a distinctive behaviour in terms of controlling factors spatio temporal distribution and kinematics and consequently the proposed differentiation may have a practical utility the vast majority of the subsidence damage identified in the area occurs within the boundaries of pre existing sinkholes identifiable in old aerial photographs and topographical maps this fact demonstrates that the application of preventive planning strategies based on detailed geomorphological maps would have allowed avoidance of most of the large financial losses caused by subsidence in the area of the order of hundreds of thousands of euros per year

dinsar measurements of ground deformation by sinkholes mining subsidence and landslides ebro river spain differential interferometric synthetic aperture radar dinsar has been applied to detect and measure ground deformation in a stretch of the ebro river valley spain excavated in salt bearing evaporites the capability of the small baseline subset sbas dinsar technique to detect ground displacement is analyzed comparing the dinsar results with the available geomorphological information the deformation map derived from 27 european remote sensing ers satellite images covering more than five years provides sub centimeter displacement measurements in zones coinciding with known active sinkholes and landslides moreover the map provides the first account of mining subsidence in the area the measured deformation rates reach 1 68 cm y for the sinkholes 0 80 cm y for the landslides and 1 45 cm y for the area affected by mining subsidence the sbas dinsar technique provided deformation measurements in a small proportion 5 10 of the known active sinkholes and landslides this limitation is mainly due to the lack of coherence in agricultural areas the spatial resolution of the deformation map pixel size of 90 m and the parallelism between the ers satellite line of sight and the linear escarpment on which most of the landslides occur despite this the interferometric technique provides valuable data that complement traditional geomorphological studies including the quantification of the deformation phenomena the identification of mining subsidence otherwise only recognizable by geodetic methods and the detection of creep deformation which might correspond to premonitory indicators of catastrophic sinkholes and landslides capable of causing the loss of lives detailed dinsar studies combined with field data would be required to improve the analysis of each deformation area copyright 2009 john wiley sons ltd

alluvial dolines in the central ebro basin spain a spatial and developmental hazard analysis abstract alluvial dolines are abundant in quaternary terraces and pediments overlying neogene gypsum in the zaragoza area central ebro basin spatial analysis and experimental simulation show that sulphate content in the groundwater grain size of the detrital cover topography of the tertiary quaternary boundary annual variation of the water table and thickness of the detrital cover are the main factors controlling their development taking into account these variables a theoretical spatial hazard model has been elaborated expressed as a mathematical equation and a hazard map both experiments and field data show a high correspondance between two basic mechanisms of evacuation and subsidence dragging slow subsidence and collapse of cavities and two basic types of morphology and internal structure of dolines basin doline funnel structure and well doline vault structures respectively a genetic classification of dolines and some evolutionary patterns based on these criteria are developed historical changes observed in doline distribution as well as field surveys of urban damage and microtopographic profiles allow us to evaluate the present day activity of dolines local subsidence rates measured in urban areas range from 2 5 to 10 cm year although doline generation and reactivation in the whole area tend to be compensated by filling by human activity

mapping subsurface karst features with gpr results and limitations ground penetrating radar gpr has been applied with relative success to locate paleo collapses and cavities and to detect and characterise karst one of its main advantages is that while the penetration depth is limited to several tens of meters or even just several meters the obtained resolution can be in the scale of centimeters in this paper we illustrate the applicability of gpr prospecting to the study of alluvial karst and the structures associated with subsidence areas gpr radargrams obtained with two central frequency antennas 50 and 100 mhz are balanced against direct observation of geological features of collapse structures in vertical exposures of gravel quarries gpr surveys offer the possibility of obtaining nearly continuous vertical cross sections of the subsoil and integration of data within a 3d frame however the study of the internal structure of the subsoil by means of the gpr profiles has been usually neglected in this work we show that some hints about the evolution of individual dolines can be established from the study of the geometry of the sedimentary filling by means of gpr the obtained results indicate that gpr allows to characterise the structures associated with karst features and can therefore be useful evaluating hazard susceptibility in doline fields because 1 when no surface evidences exists it permits the detection of karst hazards in the subsoil and 2 when surficial evidences of karst activity are present it permits the characterisation of processes associated with subsidence

river response to quaternary subsidence due to evaporite solution gallego river ebro basin spain abstract the stream terrace evolution of the gallego river during the quaternary was controlled by both climatic change and subsidence quaternary terrace deposits overlying tertiary clay and limestone are between 2 and 5 m thick whereas above evaporite formations the alluvial deposits may be as much as 110 m thick chronologically the first period of alluvial thickening involved the stream terraces t2 105 m above the present thalweg t3 95 m and t4 85 m which have been dated by paleomagnetic reversals as matuyama pre 780 000 the second subsidence period affected the deposits of the stream terrace t9 30 dated as brunhes post 780 000 in both thickening periods the subsidence was due to solution of the underlying evaporite formations halite and gypsum presumably during intervals of high water flow in the proposed model the valley subsidence was balanced by stream aggradation maintaining the river equilibrium profile the subsidence recorded in the alluvial deposits shows a complex spatial and temporal evolutionary pattern and total subsidence was assumed to be equal to the alluvial thickening for each subsidence period reaching up to 165 and 25 m respectively

late quaternary fluvial dynamics of the jarama river in central spain the jarama river and its catchment provide a valuable natural archive to study and reconstruct past environmental conditions in central spain this region is highly prone to changes in the hydrological cycle under predicted climate warming in particular with respect to aridity periods rainfall variability and the occurrence of extreme flood events this paper presents 15 exposures covering a time span of the last 44 ka which were documented in the field and of which seven exposures were soil chemical analyzed regarding soil texture organic matter as well as carbonate and iron content ages are based on radiocarbon dating on 32 samples latest holocene sediments were found within the channel belt where permanent remobilization of sediments takes place due to the migration of the meandering river course in more distal floodplain positions sediment sequences show a complex fluvial architecture referring to periods of varying character and intensity of alluviation as well as periods of geomorphic stability indicated by soil formation furthermore sedimentation patterns vary along different river sections aggradations of coarse gravels took place between 40 and 18 ka cal bp over the entire valley floor alluviation of fine material was documented between 17 and 16 at 7 5 between 5 1 and 3 3 at 2 8 between 2 1 and 1 5 at 1 0 and around 0 4 ka cal bp until recent times astonishingly in late holocene times between 4 2 and 3 1 ka cal bp aggradations of coarse gravels even in distal floodplain areas overlap with sedimentation of fine material in adjacent river sections pointing to a complex constellation of parameters involved periods of soil formation were detected around 43 at 31 between 16 and 12 6 after 7 5 until 5 1 between 2 8 and 2 1 and at times after 1 5 ka cal bp phases of geomorphic stagnation were found at 38 ka cal bp and for a duration of 200 years at 3 0 ka cal bp and refer to absent geomorphic or pedogenic processes all these patterns are an expression of the interaction between climatic variations tectonic impulses and human influences a comparison with other terrestrial archives enabled us to reconstruct late pleistocene and holocene palaeoenvironmental conditions on a regional scale and furthermore to link specific stages of floodplain development to prevalent influencing variables thus with emphasis on the fluvial system response a model of a cause and effect relationship is presented that concentrates on rapid climate changes long lasting climatic deteriorations and the role of human interventions

geomorphological and sedimentological features in quaternary fluvial systems affected by solution induced subsidence ebro basin ne spain abstract the quaternary evolution and the morpho sedimentary features of some of the most important rivers in spain ebro and tagus rivers among others have been controlled by subsidence due to alluvial karstification of the evaporitic bedrock the subsidence mechanism may range from catastrophic collapse to slow sagging of the alluvium by passive bending in the ebro basin the mechanisms and processes involved in karstic subsidence were studied through the analysis of present day closed depressions as well as through old subsidence depressions palaeocollapses and solution induced basins and associated deformations recorded in the quaternary alluvial sediments the gallego ebro river system is presented as a case study of channel adjustments and geomorphic and sedimentary evolution of fluvial systems in dissolution induced subsidence areas in this fluvial system evaporite dissolution during particular quaternary time intervals namely early and middle pleistocene have lead to the development of a solution induced basin approximately 30 km long by 8 km wide filled by quaternary deposits with a total thickness in excess of 190 m the main river response to balance the subsidence in the alluvial plain was aggradation in the central reach of the subsiding area and degradation both in the upstream reach and in the valley sides where alluvial fans and covered pediments may prograde over the fluvial sediments the main sinking areas are recognized in the sedimentary record by anomalous thickenings in the alluvial deposits and fine grained sediments deposited in backswamp and ponded areas