using cosmo skymed x band and envisat c band sar interferometry for landslides analysis abstract we explore new possibilities offered by the recently available x band satellite radar sensors for landslide hazard assessments on a detailed scale with particular reference to the exploitation of persistent scatterers interferometry psi techniques special attention is paid to the impact of the improved resolution of new x band radar imagery on the psi results in terms of quality and quantity of useful information this evaluation is supported by theoretical modelling as well as by the comparison of results from x band csk and c band envisat psi for two areas of interest one in italy and the other in switzerland it is demonstrated that with respect to medium resolution envisat ps processing fewer csk high resolution images are sufficient to achieve comparable precision of the mean displacement velocity estimates this together with the shorter revisit times provided by the csk constellation can be very important when dealing with emergency situations furthermore it is quantified that from about 3 to 11 times greater ps densities are obtained with the higher resolution x band data this implies more information about ground surface displacements as well as improved landslide monitoring and slope instability investigation capabilities furthermore ground displacement measurements can be interpreted without local knowledge of the focus area or in situ controls and nonetheless guide single hillslope instability assessments with support of google earth and its high resolution optical imagery this blind approach will allow one to monitor remote and poorly known regions at high risk of potentially disastrous slope failures

development and morphometry of sinkholes in coastal plains of apulia southern italy preliminary sinkhole susceptibility assessment abstract evolution of coastlines in karst areas may be strongly controlled by dissolution processes which favour the development of surface and subsurface landforms the generation of caves in these environments is commonly favoured by the mixing between fresh and brackish waters the sinkholes resulting from the upward propagation of the caves may interfere with the anthropogenic environment and cause damage to human elements property and activities to highlight the often underestimated importance of karst phenomena in coastal areas we have analyzed a coastal stretch of apulia in southern italy the study area covering an extension of about 6 km 2 is situated in the ionian coast and presents several interesting karst landforms that are generally connected to caves tens of sinkholes were mapped through field surveys multi year aerial photographs dating back to the 1940s and archival research we have performed a morphometric analysis of the sinkholes the analysis describes the main parameters of the sinkholes area length width and depth and the control exerted by the main discontinuity systems in the area the detrimental effects derived from interaction between human environment and these karst landforms is also under consideration a sinkhole susceptibility map which may provide useful information for planners developers and the insurance industry has eventually been produced through application of a decision tree model

pore water extraction from the unsaturated and saturated zones a simple inexpensive method for extracting pore water from unsaturated soils which uses a combination of immiscible fluid displacement suction and mechanical compression is described this method uses a squeezing chamber to contain the unsaturated sediments in aluminum core tubing to prevent exposure of the sediments and pore water to atmospheric o2 and subsequent oxidation reactions geochemical artifacts resulting from high compression squeezing are prevented by maintaining the pressure applied during the squeezing at a minimum comparison of squeezed profiles with field measured profiles of ph eh oxidation reduction potential alkalinity and metal speciation indicates good agreement between these parameters using this method depending on the water content of the sediments a range of water volumes several millilitres to excess of 100 ml can be extracted from a single core section 7 6 cm in diameter by 20 cm long pore water was produced immediately from sediments at near saturated condition

sinkholes in italy first results on the inventory and analysis the italian geological survey apat carried out field surveys and analysis of collapse phenomena sinkholes in italy the main goal of the project is to collect geological geomorphological geochemical and hydrogeological data about the sinkhole prone areas in italy in order to develop a spatial database of the characteristics of each phenomenon the preliminary results of this study provide information on the distribution geological setting and monitoring and remediation actions associated with these natural collapses in italy many italian regions are affected by these natural disasters some of them are caused by karst collapses or anthropic activity however some occur in areas characterized by buried carbonate bedrock up to 190 m as well as by peculiar geological structural and geochemical scenarios in these areas it is not reasonable to ascribe the formation mechanism to karst activity instead these types of cavities quickly develop in terrains with a variable granulometry often in connection with upwelling fluids in this work some natural specific cases have been studied in order to define the relationships between the geology regional tectonic elements mineral spring waters and strong gas vents and the genesis of the sinkholes a first attempt of sinkhole classification is also presented

the influence of loess cave development upon landslides and geomorphologic evolution a case study from the northwest loess plateau china abstract loess caves landslides collapses bank erosion and soil erosion which are independently and interactively shaping the modern loess landscape are widely distributed across the chinese loess plateau the study area is located in a small watershed in huining county gansu province which is one of the areas with the strongest development of loess caves across the loess plateau this area is an ideal site for studying geological hazards and geomorphic evolution on the loess plateau seventeen landslides and 176 loess caves with a density of 887 units km2 were investigated with a uav unmanned aerial vehicle and mapped by gis geographic information system using high resolution uav images and topographic data we carried out an interpretation of loess caves bank erosion and landslides studied the spatial distribution and developmental patterns of loess caves landform morphology and the relationship between loess caves and landslides based on gis spatial analysis mathematical statistics and field surveys and analyzed the influence of loess microtopography on slope landforms finally six typical evolutionary models of soil erosion loess cave development landslide occurrence barrier dam formation are preliminarily proposed the primary slope stage early cave stage accelerated cave stage cave connecting stage landslide creeping stage and landslide dam forming stage this study is a useful exploration and an attempt to reveal the influence of loess cave development on slope stability and disaster chain effects

subsidence rings and fracture pattern around dolines in carbonate platforms implications for evolution and petrophysical properties of collapse structures abstract this work focuses on the study of collapse dolines which are the most expressive collapse structures in carbonate rocks and their relations with preexisting and syn collapse fractures the study area has two fracture sets that were formed before folding early n s e w and late ne sw nw se striking sets which concentrate most of the dissolution in the region and allow the formation of the dolines we define subsidence rings as the circular and ellipsoidal concentric zones around collapse structures which are subjected to subsidence due to major collapses and represent locations where new fractures are formed in these subsidence rings the downfaulted topography plunges towards the doline center and reaches more than 10 m in relation to unaffected areas away from dolines the topographic data indicate that the mean radius of the combined rings is twice the radius of the collapse which corresponds to the closed depression due to failure and downfall of blocks the subsidence process enlarges links preexisting fractures and forms a new set of semicircular concentric opening mode fractures here named collapse fractures increases in the apertures and densities of these fractures occur towards the dolines which increases fracture porosity around collapse structures fractures are reactivated as normal faults close to the main collapse at the doline edge this increase in fracture intensity could represent an indicator of permo porous quality improvement in these areas further this fracturing increases structural instability raising the risk of accidents in areas built on soluble carbonate rocks since the affected area may be much larger than previously predicted subsidence rings around collapse dolines could merge with other rings from neighboring collapse structures and potentially increase porosity and permeability as well as linking areas in carbonate reservoirs

geological and geotechnical characteristics of some loess and loessic soils from china and britain a comparison abstract derbyshire e and mellors t w 1988 geological and geotechnical characteristics of some loess and loessic soils from china and britain a comparison eng geol 25 135 175 loess and loessic deposits cover some 630 000 km 2 of the surface of mainland china the loess plateau of shanxi shaanxi gansu and ningxia being the type region of this formation loess thickness generally exceeds 100 m over large areas of the loess plateau the maximum recorded thickness being 335 m in eastern gansu province near the city of lanzhou in britain loess and loessic deposits form part of a group of materials collectively known as brickearth they occur predominantly as sporadic accumulations in the southeast of england and rarely attain a thickness of more than four metres despite their geographical separation the deposits from china and britain have a remarkable similarity in some of their physical and geotechnical characteristics samples from both locations have been examined and tested in the laboratory and the results are presented the scope of the testing programme involved mineralogical analyses soil microfabric studies using a scanning electron microscope index testing including plasticity grading and density measurements and the investigation of the compressibility characteristics of the soils with particular reference to their susceptibility to collapse a soil structure model based on scanning electron microscope studies is presented and discussed in relation to the perceived mode of formation of the soils and their postdepositional history

combined use of space borne sar interferometric techniques and ground based measurements on a 0 3km2 subsidence phenomenon abstract the built up area of the village hilsprich lorraine france is affected by a subsidence phenomenon localized over a few hundred square metres causing damage to buildings in this study differential sar interferometry dinsar was used to estimate the boundaries of the subsidence in order to optimize ground based monitoring networks levelling and geophysical measurements estimate the maximum deformation and highlight the evolution of the phenomenon previously unknown due to insufficient historical ground based data the study was based both on l band alos palsar sar data and c band envisat asar data the interest in palsar data lies in its better performance for insar with respect to c band data on the affected non urban areas such as fields and farmlands where in addition conventional techniques such as topographical survey information were limited and had often not been carried out before the first damage was observed conventional dinsar based on palsar data processing for the 2008 2010 period identified the boundary of the subsidence area and estimated its maximum magnitude the psi technique in the asar archive gave information regarding the beginning of the subsidence the precision of the dinsar results was consistent with the topographical data in locations where this information was known and therefore favours the sar interferometric techniques in this context combined with the knowledge of the regional geological and structural setting together with results from ground based electrosounding the results of the study established a basis for an increased understanding of the subsidence phenomenon which was revealed to affect an elliptical bowl shaped area due to salt dissolution

flank instability of stromboli volcano aeolian islands southern italy integration of gb insar and geomorphological observations abstract stromboli is characterized by frequent explosions of variable energy and periodically interrupted by more energetic blasts emitting large volumes of material the pressurization of a volatile poor high porphyritic magma column that is gas recharged by the deep seated volatile rich low porphyritic magma precedes such events and produces deformations on the nw flank of the volcano sciara del fuoco by integrating geomorphological observations with long term displacements from ground based interferometric radar since december 2007 we identified two landslides whose movements are strongly related with volcanic activity movement patterns obtained through a novel long term analysis of gb insar data permitted us to hypothesize the type of movement and depth for both landslides furthermore their position allowed us to affirm that the effusive vent formed in 2007 at 400 m a s l was the result of the deflection of a feeder dike caused by landslide fractures thus showing the important role of geomorphological discontinuities in volcanic environments

integrating radar and laser based remote sensing techniques for monitoring structural deformation of archaeological monuments ground based synthetic aperture radar interferometry gbinsar and terrestrial laser scanning tls were purposely integrated to obtain 3d interferometric radar point clouds to facilitate the spatial interpretation of displacements affecting archaeological monuments the paper describes the procedure to implement this integrated approach in the real world situations of surveillance of archaeological and built heritage targeted tests were carried out on the case study of the domus tiberiana sited along the northern side of the palatino hill in the central archaeological area of rome italy and displacements of the monument were monitored over almost one year of acquisition the gbinsar tls integration provided updated information about the condition of the archaeological structures in relation to their history of instability mechanisms and did not highlighted a general worsening for the stability of the entire monument point wise and prompt detection of displacement anomalies and or sudden changes in displacement trends proved the suitability of the method to support early warning procedures also to evaluate effects on the masonry due to human activities

development of collapse sinkholes in areas of groundwater discharge abstract collapse sinkholes are found in groundwater recharge zones throughout the world they cause substantial loss of property each year and occasional fatalities in such settings the formation of these features occurs through the downward migration of regolith into karst voids the presence of a void in the bedrock and sufficient seepage pressure or gravitative force in the regolith is required for their creation we investigated the development of cover collapse sinkholes in an unusual setting areas of groundwater discharge rather than recharge upward hydraulic gradients and the likelihood of groundwater saturated with respect to calcite are difficult to reconcile with standard models for collapse development short flowpaths or renewed groundwater aggressivity towards calcite via mischungskorrosion thermally driven circulation or deep seated gaseous sources are hypothetical mechanisms that could generate the subsurface voids that are needed to allow cover collapse development in discharge areas for the two field sites in central italy that we investigated calculated carbon dioxide partial pressures in springs ranged from 7 38 10 2 to 7 29 10 1 atm this indicates that deep seated gaseous sources are most likely the mechanism allowing the development of the sinkholes groundwater is recharged in surrounding limestone massifs the water moves through the carbonates and becomes saturated with calcite as it circulates deeply in to the adjacent valleys it mixes with deep seated waters and gaseous fluxes from major fault systems acquiring renewed aggressivity towards calcite finally the water ascends into confined aquifers in the valley fill and dissolves carbonate material present within leading to surface collapse

ground based insar reveals conduit pressurization pulses at stromboli volcano at stromboli volcano southern italy only few minor precursors gas output have been identified for major strombolian explosions we use ground based interferometric synthetic aperture radar gbinsar technology to monitor the displacement rate of the summit area of stromboli we analysed the 2009 2011 period the analysis of the displacement rate has been performed by dividing the summit zone monitored by the gbinsar into three regions corresponding to the edge of the crater area 1 and 2 and to the slope of the ne crater 3 pulses of rapid expansion of sector 3 of variable duration and amplitude appear in coincidence with periods of intense activity that include lava flows and major explosions we associate this expansion with the pressurization of the magma column that is recharged by deep derived gas promoting the onset of major explosion dominated activity

sinkhole monitoring and early warning an experimental and successful gb insar application abstract sinkholes represent a natural risk that may hit catastrophically without clearly detectible precursors however they are often overlooked by people and administrators therefore sinkhole monitoring and associated early warnings constitute important research topics but currently only a few papers about sinkhole prediction can be found in this paper an experience of sinkhole monitoring and early warning with gb insar is described the latter is a highly precise instrument that is able to produce displacement maps with metric spatial resolution the described activities were carried out on elba island central italy where karstified limestone set off the occurrence of nine sinkholes since 2008 all within less than 3000 m2 causing major damage to an important road and many indirect losses in 1 year of monitoring two deforming areas were detected and the point where a sinkhole was about to propagate to the street level was predicted thus permitting the preventive closure of the road the deformation area was larger than the hole generated by the sinkhole thus showing a subsidence that continued for a prolonged time even after the cavity was filled up the occurrence of a 1 5 m wide sinkhole undetected by the gb insar also showed the lower detection limit of the instrument

uranium series disequilibrium in a young surficial uranium deposit northeastern washington u s a a recently discovered ore grade accumulation of u in organic rich sediments of late quaternary age provides an opportunity for studying the early association of u u daughters and organic matter in a natural setting the u occurs in valley fill sediments of peat peaty clay silt and sand along the north fork of flodelle creek stevens county washington radiometric techniques delayed neutron high resolution gamma ray spectrometry thin source alpha spectrometry were employed to determine the abundance and distribution of u series nuclides the extent of secular equilibrium within the u decay series and the apparent u series ages of u incorporation sixteen lithologically distinct intervals were sampled from a 292 cm core uranium contents range from 140 to 2790 ppm and are positively correlated with organic contents measured alpha activity ratios of 234u 238u 1 31 1 38 are very similar to those reported in coexisting waters suggesting a rather constant isotopic composition of introduced u much lower th contents of 10 40 ppm are controlled by the type and abundance of silicate detritus the youth of the host sediments 15 000 a and the paucity of associated radioactivity suggested large excesses of u relative to radioactive daughters and such excesses were observed particularly in the shallowest intervals apparent ages of u emplacement determined by the alpha activity ratio of 230th daughter to 234u parent show a general increase with depth and fair agreement with estimated depositional ages this observation suggests dominantly syndepositional or early post depositional emplacement of u followed by decay generated buildup of 230th daughter with time however interval by interval comparisons of the relative abundances of other daughters particularly 226ra and 210pb indicate variability caused by processes other than closed system growth and decay probably because chemically diverse daughters that are decay generated in situ have differing mobilities and because upwelling ground water continuously adds more u and minor amounts of daughters if 230th is considered the least susceptible to these modifications the data suggest some addition of 234u in the deepest intervals and some loss of 226ra and or gain of 222rn throughout the studied core

integrated geophysical survey in a sinkhole prone area microgravity electrical resistivity tomographies and seismic noise measurements to delimit its extension abstract detection forecasting early warning and effective monitoring are key aspects for the delimitation of sinkhole prone areas and for susceptibility assessment and risk mitigation to attain these goals direct and indirect techniques can be employed and the integration of different indirect non invasive geophysical methods including 2d and 3d electrical resistivity tomography microgravity and single station seismic noise measures was carried out at il piano elba island italy where at least nine sinkholes occurred between 2008 and 2014 the most likely origin for these sinkholes had been considered related to net erosion of sediment from the alluvium caused by downward water circulation between the aquifer hosted in the upper layer quaternary alluvial deposits and that in the lower triassic brecciated dolomitic limestone and cretaceous slate the integrated geophysical survey therefore was carried out a to differentiate shallower from deeper geological layers b to detect possible cavities that could evolve into sinkholes c to suggest possible triggers and d to delimit the sinkhole prone area the results of the integrated geophysical surveys suggest that the study area is mainly characterised by paleochannels and that the sinkhole prone area boundaries correspond to these paleochannels

use of a total station to monitor post failure sediment yields in landslide sites of the shihmen reservoir watershed taiwan abstract landslides have both immediate and extended duration effects on sediment discharge examining the role of post failure soil loss sediment yield of landslides is essential for basin management purposes the comprehensive measurement of sediment production of existing landslides could provide a better understanding in this aspect this study investigated the post failure sediment yield of 13 landslide sites in the shihmen reservoir watershed taiwan during the rainy seasons of 2006 and 2007 using a total station our study showed that soil loss is mainly controlled by rainfall conditions and the geometric and geographic characteristics of each landslide can significantly influence the efficiency of sediment delivery we also observed that rainfall is important in determining landslide retrogression enlargement although vegetation in the landslide area increases with time we obtained a large amount of landslide measurement data which could be useful for future landslide modeling we suggest two regression models for estimating gross soil loss using cumulative rainfall the estimated gross soil loss values of 0 78 to 1 06 m yr 1 are equivalent to 18 096 to 24 592 t ha 1 yr 1 using these estimates we assessed the sources of sediment in the watershed and found that the ratio of landslide erosion soil loss after landsliding and soil erosion from other parts of the watershed was approximately 66 31 3 this study implies that remedying existing landslides is more effective than any other solution in reducing sediment production in the watershed

improving sinkhole hazard models incorporating magnitude frequency relationships and nearest neighbor analysis abstract this work presents a methodology for elaborating sinkhole hazard models that incorporate the magnitude and frequency relationships of the subsidence process the proposed approach has been tested in a sector of the ebro valley mantled evaporite karst where sinkholes largely induced by irrigation practices have a very high occurrence rate 50 sinkholes km 2 yr in this area covering 10 km 2 a total of 943 new cover collapse sinkholes were inventoried in 2005 and 2006 multiple susceptibility models have been generated analyzing the statistical relationships between the 2005 sinkholes and different sets of variables including the nearest sinkhole distance the quantitative evaluation of the prediction capability of these models using the 2006 sinkhole population has allowed the identification of the method and variables that produce the most reliable predictions the incorporation of the indirect variable nearest sinkhole distance has contributed significantly to increase the quality of the models despite simplifying the modeling process by using categorical rather than continuous variables the best susceptibility model generated with the total sinkhole population and the selected method and variables has been transformed into a hazard model that provides minimum estimates of the spatial temporal probability of each pixel to be affected by sinkholes of different diameter ranges this transformation has been carried out combining two equations derived from the more complete 2006 sinkhole population one of them expressing the expected spatial temporal probability of sinkhole occurrence and the other the empirical magnitude and frequency relationships generated for two different types of land surfaces which control the strength of the surface layer and the size of the sinkholes the presented method could be applied to predict the spatial temporal probability of events with different magnitudes related to other geomorphic processes e g landslides

sinkhole occurrence monitoring over shallow abandoned coal mines with satellite based persistent scatterer interferometry abstract unexpectedly occurring sinkholes caused by shallow submerged voids are one of the key problems of intensively built up post mining areas five percent of poland s territory is still under the influence of post mining deformation impending sinkholes which tend to develop randomly over very large areas cannot be detected by using traditional geophysical methods moreover geodetic measurement methods like global positioning system gps analyses tachymetry laser scanning or photogrammetry may be useful only for the registration of the dimensions and locations of sinkholes that have already occurred here we investigate an area in upper silesia poland where 345 sinkholes were recorded over a period of more than 20 years 1992 2013 most of the events occurred in intensively built up areas and thus these sinkholes posed a direct threat to the population in the test area 11 sinkholes were detected with a maximum depth of 16 m and maximum dimension of 25 m the root cause of sinkhole formation was the collapse of post mining shallow voids we used satellite radar technology to detect and monitor ground movements potentially associated with the impending sinkholes the findings showed that the application of persistent scatterer interferometry can support the identification of zones where sinkholes will occur given adequate spatio temporal sampling a stack of envisat synthetic aperture radar sar images acquired between march 2003 and august 2010 was used in the analysis and the results confirmed that precursory ground movements were detectable at an early stage of sinkhole development the land subsidence rate observed prior to sinkhole collapse was not constant in time accelerated ground movements within 100 m of an observed sinkhole were detected we conclude that satellite measurements may provide significant support in the early identification of areas prone to sinkhole occurrence

review on sinkhole monitoring and performance of remediation measures by high precision leveling and terrestrial laser scanner in the salt karst of the ebro valley spain abstract the need to apply sinkhole remediation and monitoring programs is increasing concurrently with the rising engineering impacts of sinkholes in many regions however there is a significant gap in the scientific literature regarding the assessment of the performance of remedial works through subsidence monitoring monitoring techniques have experienced significant advances in the last few years thanks to the advent of new technologies this work presents a review of sinkhole monitoring methods and discusses some practical considerations about their capabilities and limitations it also documents a monitoring program high precision leveling and terrestrial laser scanner and the concurrent remedial works cement based and polyurethane grouting carried out in a highly active sinkhole that affects a flood control dike and the adjacent village of alcala ne spain the subsidence activity in the sinkhole is characterised by progressive sagging and the development of catastrophic nested collapses monitoring data reveal subsidence expansion and acceleration in the sector of the dike treated by polyurethane grouting above the main cavities in contrast subsequent cement based grouting of the large cavities significantly reduced subsidence rates displacement data also indicate substantial subsidence enhancement following flood recession and the associated water table drop buoyancy loss this case study illustrates that high precision leveling and terrestrial laser scanning are adequate complementary methods for monitoring specific sinkholes characterised by very high accuracy and detailed spatial resolution respectively

an evaluation of the use of the chromous chloride reduction method for isotopic analyses of pyrite in rocks and sediment abstract the use of chromous chloride reduction as a preparation technique for isolation of pyrite sulphur for isotopic analysis has been assessed a small but consistent fractionation is introduced by reduction of pyrite to h 2 s enriching the yield in 34 s by 0 55 0 14

evaporite karst and sinkholes a synthesis on the case of camaiore italy in 1995 a sinkhole suddenly formed at camaiore tuscany italy causing destruction or heavy damages to several houses and resulting in the evacuation of many people to understand the causes for the formation and evolution of the collapse surface and underground geologic features were investigated and reconstructed on the basis of geologic and geognostic surveys the sinkhole area is underlain by thick alluvial deposits that cover a bedrock consisting of the calcare cavernoso formation this formation results from hydration and dissolution of triassic evaporites and has a characteristic spongy and vacuolate texture the bedrock contains karst cavities generally filled by breccia and or alluvial materials thus the sinkhole disaster could be ascribed to deep collapse of a cave in the bedrock and might be considered a distant effect of ancient karst phenomena in evaporites

porewater sulphur geochemistry and fossil preservation during phosphate diagenesis in a lower cretaceous shelf mudstone lower cretaceous mudstones exposed at speeton in north yorkshire uk contain lobsters and burrows preserved in diagenetic phosphate concretions isotopic compositions of sulphur in both diagenetic sulphide and structural sulphate in diagenetic phosphate have been measured in an attempt to constrain diagenetic porewater chemistry the occurrence of phosphatized and pyritized lobsters and similarly preserved burrows allows a detailed comparison of these microenvironments with the host sediments host sediments are extensively bioturbated and characterized by very light sulphide isotopic compositions mean sulphide 34s 48 3 3 1 n 19 and sulphate isotopic compositions that are lighter than lower cretaceous seawater sulphate mean sulphate 34s 8 7 3 2 1 n 19 these isotopic values can be explained by the action of bioturbating macrofauna the introduction of oxygen in ventilating seawater results in the oxidation of early formed isotopically light pyrite resulting in porewater sulphate that is enriched in 32s subsequent pyrite formation via bacteriogenic reduction of isotopically light porewater sulphate leads to the formation of isotopically light pyrite whilst residual porewater sulphate apparently remains relatively enriched in the 32s isotope sulphur isotopic values for the burrows are very different sulphide isotopic compositions average 34 4 0 4 1 n 3 and sulphate isotopic compositions average 14 4 6 6 1 n 4 these isotopic compositions are the result of rapid development of closed system conditions in burrows resulting in the build up of acidity necessary for phosphate precipitation and coprecipitation of isotopically light sulphate formed by oxidation of isotopically light sulphide surrounding the burrows lobster shell isotopic compositions fall between these two groups on the basis of their isotopic compositions some lobsters appear to have died close to the sediment water interface whilst others appear to have been buried in burrows prior to death

contribution of water geochemistry and isotopes δ18o δ2h 3h 87sr 86sr and δ11b to the study of groundwater flow properties and underlying bedrock structures of a deep landslide a comprehensive understanding of bedrock lithology and groundwater circulation is necessary to identify areas prone to landslide initiation and reactivation this necessity is particularly required in the case of outcroppings of weak rocks such as gypsum that due to their high solubility and low mechanical strength can promote slope deformation with the development of caves and collapses in the upper secchia river valley where gypsum outcrops extensively and is covered by landslide deposits an accurate identification of the gypsum outcrops and their distribution is needed to reduce the damage to urbanized slopes in this paper a hydrologic and geochemical approach is used in the montecagno landslide to identify the origin flow paths and transit time of groundwater circulating inside the landslide body and to identify gypsum deposits and their distribution in the bedrock the results of groundwater level monitoring 18o 2h and 3h isotope analyses and flowpc modelling suggest a local and recent origin of the groundwater hosted in shallow flow paths inside the landslide chemical and isotope 87sr 86sr 11b analyses offer evidence of the presence inside the landslide of small blocks of gypsum that due to their dimensions probably have a minor influence on landslide stability this research demonstrates that the methodology used can provide satisfactory information about bedrock structures and their hydrological aspects

morphological and kinematic evolution of a large earthflow the montaguto landslide southern italy article ml ong earthflow in the southern apennines of italy following an analysis of th ed ifferent methods and techniques available to measure surface modifications caused by a large earthflow we selected a combination of monitoring techniques com patible with the montaguto case study we exploited i visual interpretation of aerial and satellite imagery ii quantitative analysis of six digital elevation model s dems covering the landslide area and iii al arge set of high accuracy three dimensional topographic measurements captured by three robotised total stations rtss in tegration of the results obtained from the different monitoring techniques allowed us to investigate the long multi decadal and short seasonal term evolution of the montaguto earthflow in the 58 year period 1954 2011 the examination of the available aerial satellit ea nd hill shade images revealed ac yclic long term behaviour of mass movements of different types in the rio nocelle catchment occupied by the recent montaguto earthflow the combined analysis of the six dems allowed measuring the material eroded from the landslide crown area v 1 4 10 6

234u238u and 230th234u activity ratios in mineral phases of a lateritic weathered zone abstract a selective phase extraction procedure was developed for the identification of the significant phases of a typical deep soil profile sampled in the vicinity of the ranger no 1 uranium ore body alligator rivers region n t australia the significant phases were identified as amorphous iron oxide crystalline iron oxide and a clay quartz resistate the distribution of 238 u 234 u 230 th and 226 ra between the phases was measured the results indicated that the amorphous iron oxide phase is in adsorption desorption equilibrium with the ground water the crystalline iron oxide phase contains a chemical control the kinetics of which are commensurate with or less than the half life of 230 th 7 52 10 4 y the clay quartz resistate is enriched in 238 u descendants in such a way that they are not readily accessible to the ground water

15n isotope biogeochemistry and natural denitrification process in groundwater application to the chalk aquifer of northern france the use of 15n natural isotope tracing in an aquifer contained within chalk rocks in northern france indicates that under certain hydrogeological conditions major denitrification occurs at the boundary where the aquifer becomes confined the nitrate concentrations decrease in the direction of groundwater flow accompanied by an exponential increase in 15n expressed in 15n of the residual nitrate this is characteristic of kinetic isotope effects which accompany the reduction of the nitrate ion during denitrification hydrogeochemical and bacteriological observations confirm this process natural isotope tracing also permits this process to be distinguished from local dilution with nitrate free surface water which would entail a major drop in nitrate values without 15n isotopic enrichment a model is proposed to explain the relatively small observed magnitude of the isotopic fractionation effect

evaluation of trenching ground penetrating radar gpr and electrical resistivity tomography ert for sinkhole characterization this paper explores the suitability and advantages of combining the trenching technique with geophysical surveys ground penetrating radar gpr and electrical resistivity tomography ert for sinkhole characterization in a mantled karst area the approach is applied to two active sinkholes concealed by anthropogenic deposits and formed by contrasting subsidence mechanisms collapse and sagging the ert section acquired across the collapse sinkhole images the clayey fill of the depression as an obvious low resistivity area showing the approximate location of the sinkhole edges spatially dense gpr surveys provide information on the position of the boundaries of the concealed subsidence structures and their three dimensional 3d internal geometry revealing the dominant subsidence mechanism we illustrate the impact of several factors on the quality of the gpr data such as sinkhole size nominal frequency of the antennas antenna shielding and the presence of backfilled excavations and above surface objects trenches provided detailed information on the subsurface structure of the sinkhole subsidence magnitude partitioning of the strain and the position of the sinkhole edges especially when they are deep enough and excavated across the central sector and perpendicular to the boundaries the stratigraphic and structural relationships observed in the trench were then used to infer the spatial evolution of the sinkholes e g enlargement their kinematic behavior episodic versus progressive and to differentiate discrete subsidence events and their associated magnitude numerical dates were used to estimate average subsidence rates and the recurrence of subsidence events such integrated data sets may be used as an objective basis to forecast the future behavior of potentially damaging sinkholes and to assess the associated hazard and risk copyright 2013 john wiley sons ltd

ert gpr insar and tracer tests to characterize karst aquifer systems under urban areas the case of quebec city abstract urban infrastructures built over karst settings may be at risk of collapse due to hydro chemical erosion of underlying rock structures in such settings mapping cave networks and monitoring ground stability is important to assure civil safety and guide future infrastructure development decisions however no technique can directly and comprehensively map these hydrogeological features and monitor their stability the most reliable method to map a cave network is through speleological exploration which is not always possible due to restrictions narrow corridors passages or high water levels borehole drilling is expensive and is often only performed where the presence of karsts is suggested by other techniques numerous indirect and cost effective methods exist to map a karst flow system such as geophysics geodesy and tracer tests this paper presents the outcomes from a challenging application in quebec city canada where a multidisciplinary approach was designed to better understand the groundwater dynamics and cave paths two tracer tests in groundwater flowing through the cave system indicated that water flows along an approximately straight path from the sinking stream to the spring it also suggests the presence of a parallel flow path close to the one already partially mapped this observation was confirmed by combining ground penetrating radar gpr and electrical resistivity tomography ert techniques and ultimately by observing voids in several boreholes drilled close to the main cave path lowering the water levels at the suspected infiltration zone and inside the karst the infiltration cracks were identified and the hydraulic link between them was confirmed in fact almost no infiltration occurs into the karst system when the water level at the sinking stream drops below a threshold level finally sar interferometry insar using radarsat 2 images detected movements on few buildings located over a backfilled sinkhole intercepted by the karst system and confirmed the stability of the rest of the karst area the knowledge of the flow system described in this paper is used by policy makers to assure civil security of this densely populated area

a landslide forecasting model using ground based sar data the portalet case study this paper presents a kinematic study of the portalet landslide sallent de gallego central spanish pyrenees which was triggered by the construction of a big parking area at the toe of the slope a description of the landslide from a geomorphological point of view is first introduced the measurements of displacement performed by conventional total station inclinometers and differential gps and advanced gb sar ground monitoring techniques are presented and gb sar and dgps datasets are compared the correlation between measured displacements and rainfall series indicates that the landslide is very sensitive to rainfall the continuous gb sar measurements from the 5th of october 2006 to the 21st of november 2006 at a rate of 1 h were used to calibrate a simple 1d infinite model by back analysis the model includes a viscoplastic behaviour and takes into account directly the known daily rainfall intensity and the dissipation of the excess pore fluid through a simple consolidation equation prediction was made in an extended period of time from may 2006 to july 2007 and compared to the dgps measurements

bayou corne louisiana sinkhole precursory deformation measured by radar interferometry catastrophic sinkholes are formed through the collapse of natural or human made subterranean caverns and are common in areas with evaporite and carbonate rock despite their danger advance warning of these events is rare we report a measurement of precursory surface deformation of as much as 260 mm derived with interferometric synthetic aperture radar insar and evident over a month before surface collapse at the site of the bayou corne louisiana usa sinkhole that formed in august 2012 data collected by the airborne uninhabited aerial vehicle sar uavsar instrument were used for the study analysis of data acquired from two flight tracks with near opposing imaging geometries reveal a deformation pattern consistent with compressive loading at the surface due to loss of support from a subterranean cavity collapse related to texas brine oxy geismar well 3 the precursor deformation was nearly entirely horizontal i e oriented along the surface and manifested as movement of surface material toward the location where the sinkhole later formed the sinkhole formed in the area with the largest gradient in surface strain but did not cover the full extent of the precursory deformation detected with radar this work suggests that insar data collected operationally for hazard monitoring could in some cases identify sinkhole development before surface collapse and decrease subsequent danger to people and property

sinkhole distribution in a rapidly developing urban environment hillsborough county tampa bay area florida sinkhole formation in florida is a common event the florida karst plain is significantly altered by human development and sinkholes cause considerable property damage throughout much of the state we present in this paper a morphometric analysis of karst depressions in the tampa bay area and the relation with the known distribution of sinkholes we selected the tampa bay area because it is particularly susceptible to the evolution of karst depressions in relation with development of the built up environment karst depressions were mapped from the 1 24 000 usgs topographic maps and a morphometric analysis was performed by using parameters such as shape circularity index perimeter area length width and orientation maps showing the distribution of depression density and the sectors with greatest areas of karst depression were produced using a gis these results were compared with data compiled from the database of sinkhole occurrences in florida maintained by the florida geological survey our analysis demonstrates that the distribution of new sinkhole occurrences differs from the distribution of existing sinkholes indicating that there are processes acting today that are influencing karst landscape formation that are different from those acting in the past

radioelements radiogenic helium and age relationships for groundwaters from the granites at stripa sweden abstract the solution of radioelements and radiogenic 4he by groundwaters in fractured rocks is dependent upon the radioelement distribution in the rock matrix and the extent of the rock water interface the 234 u 238 u activity ratio and the dissolved u rn and he contents of such groundwaters respond to changes in the flow regime with time although 234 u 238 u activity ratios change with groundwater residence time as a consequence of 234th recoil induced solution of 234u the activity ratio is strongly influenced by the u distribution within fractures by the extent of the rock water interface and by the amount of 238u in solution a model for the quantitative evaluation of these effects is presented groundwaters from depths up to 880 m in the stripa granite have variable dissolved uranium contents and 234 u 238 u activity ratios the uranium geochemistry is primarily determined by variations in flow path rather than by groundwater age dissolved radiogenic 4he in the groundwaters increases with their depth of origin and is dependent upon the u content of the granite and upon its fracture porosity it increases with groundwater residence time but movement of 4he by diffusion and transport processes make the actual groundwater age indeterminate

a genetic classification of sinkholes illustrated from evaporite paleokarst exposures in spain this contribution analyses the processes involved in the generation of sinkholes from the study of paleokarst features exposed in four spanish tertiary basins bedrock strata are subhorizontal evaporites and in three of the basins they include halite and glauberite in the subsurface our studies suggest that formation of dolines in these areas results from a wider range of subsidence processes than those included in the most recently published sinkhole classifications a new genetic classification of sinkholes applicable to both carbonate and evaporite karst areas is thus proposed with the exception of solution dolines it defines the main sinkhole types by use of two terms that refer to the material affected by downward gravitational movements cover bedrock or caprock and the main type of process involved collapse suffosion or sagging sinkholes that result from the combination of several subsidence processes and affect more than one type of material are described by combinations of the different terms with the dominant material or process followed by the secondary one e g bedrock sagging and collapse sinkhole the mechanism of collapse includes any brittle gravitational deformation of cover and bedrock material such as upward stoping of cavities by roof failure development of well defined failure planes and rock brecciation suffosion is the downward migration of cover deposits through dissolutional conduits accompanied with ductile settling sagging is the ductile flexure of sediments caused by differential corrosional lowering of the rockhead or interstratal karstification of the soluble bedrock the paleokarsts we analysed suggest that the sagging mechanism not included in previous genetic classifications plays an important role in the generation of sinkholes in evaporites moreover collapse processes are more significant in extent and rate in areas underlain by evaporites than in carbonate karst primarily due to the greater solubility of the evaporites and the lower mechanical strength and ductile rheology of gypsum and salt rocks

characterizing and monitoring a high risk sinkhole in an urban area underlain by salt through non invasive methods detailed mapping high precision leveling and gpr abstract two critical aspects for assessing the hazard and managing the risk associated with active sinkholes in developed areas are the precise mapping of the areas affected by ground instability and the quantitative characterization of the ground displacement kinematic style spatial temporal patterns rates however sinkhole site investigations typically provide a static picture of the instability phenomena and the performance of remediation measures is rarely evaluated using time series of displacement this work illustrates the practicality of a non invasive approach combining detailed mapping ground penetrating radar gpr and high precision leveling for the characterization at different time scales of the ground deformation associated with an active sinkhole in an urban area the selected highly active sagging and collapse sinkhole affects four multi storey buildings in zaragoza city spain involving direct losses higher than 15 meuro gpr data provided information on the internal structure of the sinkhole and the subsidence mechanisms the boundaries of the ground deformation zone established with the gpr data and especially high precision leveling indicate a sinkhole area two times larger than that previously proposed on the basis of airborne imagery and surface deformation features length from 100 m to 130 m the leveling profiles reveal an inner rapidly subsiding zone with vertical displacement rates as high as 3 cm yr an outer slow settlement ring and a marginal uplifting bulge with vertical displacement rates that reach 0 6 cm yr this phenomenon of marginal bulging is probably a relatively common process in sagging sinkholes which may have gone unnoticed since its identification requires the use of geodetic methods with utmost accuracy such as high precision leveling monitoring data indicate that ongoing salt dissolution significantly contributes to the active subsidence and reveal the high impact on the subsidence of water pumping from the evaporitic aquifer and the limited efficiency of a shallow compaction grouting program performed above cavities and karstification zones

definition of sinkhole triggers and susceptibility based on hydrogeomorphological analyses sinkholes represent a geological risk that is often underrated mainly due to its very localized nature in fact sinkholes occur only under particular circumstances and typically affect relatively small areas despite these characteristics the difficulty in forecasting the precise location and timing of their sudden collapse creates serious problems for civil protection authorities and urban planners in this framework identifying the mechanism and thus the triggering factor of sinkholes is strategically pivotal in developing management plans the present paper addresses the sinkhole prone area of il piano elba island central italy the integration of hydrogeological surveys coupled with a thorough study of historical maps and aerial photographs suggests that the main triggering factor in this area may not be related to water pumping from the karst aquifer as initially hypothesized instead sinkholes appear to be caused by ravelling and erosive processes occurring entirely in the sedimentary cover when heavy rainfall induces water overpressure within the superficial aquifer

basic processes and factors determining the evolution of collapse sinkholes a sensitivity study abstract collapse sinkholes are closed depressions appearing at the surface as a consequence of a complex interplay between dissolution erosion and mechanical stability in karst aquifers sinkholes are difficult to study and their locations are almost impossible to predict because of the multiple parameters involved and complex mechanisms controlling their evolution and collapse with this work we present a systematic theoretical research focused on the processes responsible for the development of collapse sinkholes splitting the evolution time in different stages we propose a conceptual model allowing decoupling of the main processes and a sensitivity study on the controlling parameters the conceptual framework is implemented with the help of a high resolution 2d karst evolution model and a simplified 3d dem mechanical model our results demonstrate that the development of a collapse sinkhole is controlled by dissolution throughout most of its evolution while the mechanical collapses occur during short time intervals the karstification is extremely sensitive to variations in the hydraulic conductivity or the amount of water flowing through the aquifer finally we discuss the hydro geological conditions which allow or not for systematic sensitivity studies

234u and238u concentration in brine from geopressured aquifers of the northern gulf of mexico basin abstract the 234 u and 238 u concentration in brine from six gulf coast geopressured aquifers has been determined the results reveal very low uranium concentrations from 0 003 to 0 03 g l and uranium activity ratios slightly greater than unity from 1 06 to 1 62 reducing conditions within the aquifers are responsible for the low uranium concentrations the uranium activity ratios observed are well below those calculated using theoretical considerations of alpha particle recoil effects this can be explained by interference with alpha recoil nuclides entering the liquid phase as a result of quartz overgrowths on sand grains and high temperature re equilibration that tends to minimize the effects of the alpha recoil process the fact that the uranium activity ratios of the brines are slightly greater than unity instead of the equilibrium value of 1 000 indicates that either the alpha particle recoil blocking and re equlibration effects are not complete or that another process is operative that enriches the fluid in excess 234 u by selectively removing uranium from radiation induced damage sites in the mineral sand grain matrix

sinkhole precursors along the dead sea israel revealed by sar interferometry the water level in the dead sea israel and jordan has been dropping at an increasing rate since the 1960s exceeding one meter per year during the last decade this drop has triggered the formation of sinkholes and widespread land subsidence along the dead sea shoreline resulting in severe economic loss and infrastructural damage in this study the spatiotemporal evolution of sinkhole related subsidence and the effect of human activities and land perturbation on sinkhole development are examined through interferometric synthetic aperture radar measurements and field surveys conducted in israel during 2012 interferograms are generated using cosmo skymed satellite images and a high resolution 0 5 m pixel elevation model obtained from lidar measurements as a result of this unique combination of high resolution data sets millimeter scale subsidence has been resolved in both natural and human disturbed environments precursory subsidence over a period of a few months occurred before the collapse of all three sinkhole sites reported in this study the centers of the subsiding areas migrated possibly due to progressive dissolution and widening of the underlying cavities filling of newly formed sinkholes with gravel and mud injections into drill holes seem to enhance land subsidence enlarge existing sinkholes and form new sinkholes apart from shedding light on the mechanical process the results of this study may pave the way for the implementation of an operational sinkhole early warning system

experimental evidence of uraninite formation from diagenesis of uranium rich organic matter abstract this study focuses on the experimental diagenetic evolution of an uranium rich lignite from the coutras uranium deposit gironde france located in eocene sediments three samples containing 6 to 15 5 wt uranium were analysed and compared to two barren samples located outside the ore deposit in a stratigraphically equivalent unit uranium in the mineralized samples is present as uranyl carboxylic complexes dry thermal maturation was simulated in a cold seal autoclave at 150 200 250 300 and 350 c at 100 mpa for 24 h with increasing temperature uranyl carboxylic complexes decompose while uraninite forms the chemical composition of the experimentally matured barren samples when plotted in a van krevelen diagram h c vs o c parallels the natural trend of land derived type ill organic matter evolution while mineralized samples are characterized by a higher loss of hydrogen above 250 c reduction to form uraninite is directly related to the dehydrogenation of lignite the resulting uraninite has a similar unit cell edge to that of natural uraninites observed in sedimentary environments uraninite not only forms in the pore space but also replaces the lignite constituents the results demonstrate that uraninite may form during thermal evolution of uranium rich organic matter during diagenesis

reconstruction of past u migration in a sedimentary deposit coutras france implications for a radwaste repository this study is focused on ancient u mobility in unconsolidated kaolinite bearing sediments from the outcrop area of the coutras u deposit gironde france the analysis of radiation induced defects by electron paramagnetic resonance spectroscopy shows significant variations among the investigated samples and provides the paleodoses due to u at coutras the highest paleodose does not correspond to the highest u concentrations indicative of a past concentration of uranium different from the present one the paleodose gives an estimate of the equivalent u concentrations eu responsible for the defect concentration assuming an age for the kaolinites and considering extreme degrees of disequilibrium among u decay chain as uncertainties of the method the comparison between the equivalent eu and normalized present day u concentrations u norm reveals past migration of u when these two concentrations are different past occurrence of u and daughters is revealed even when this radioelement has been subsequently leached indeed surface sandy beds show a slight barely significant leaching evidence of u eu u norm in contrast several samples show u norm much greater than eu which suggests past accumulation of u younger than the sediment deposition particularly in organic rich clay layers these late enrichments may reach several hundreds ppm u isotopic constraints from the literature imply that accumulation is older than 1 ma in the organic clayey beds although the time of transfer or spatial dispersion of u cannot be specified from the methodology and the limited set of samples the quantitative analysis of radiation induced defects in clays yields intensity of past radioisotope transfers at the geological timescale it is relevant for the analysis of u mobility in sedimentary natural analogues of high level nuclear waste repositories it is also complementary to classical isotopic analysis of u and th series

the ground based insar monitoring system at stromboli volcano linking changes in displacement rate and intensity of persistent volcanic activity stromboli volcano aeolian archipelago southern italy experienced an increase in its volcanic activity from late december 2012 to march 2013 when it produced several lava overflows major strombolian explosions crater wall collapses pyroclastic density currents and intense spatter activity an analysis of the displacement of the ne portion of the summit crater terrace and the unstable nw flank of the volcano sciara del fuoco depression has been performed with a ground based interferometric synthetic aperture radar gbinsar by dividing the monitored part of the volcano into five sectors three in the summit vents region and two in the sciara del fuoco changes in the displacement rate were observed in sectors 2 and 3 field and thermal surveys revealed the presence of an alignment of fumaroles confirming the existence of an area of structural discontinuity between sectors 2 and 3 high displacement rates in sector 2 are interpreted to indicate the increase in the magmastatic pressure within the shallow plumbing systems related to the rise of the magma level within the conduits while increased displacement rates in sector 3 are connected to the lateral expansion of the shallow plumbing system the increases and decreases in the displacement rate registered by the gbinsar system in the upper part of the volcano have been used as a proxy for changes in the pressure conditions in the shallow plumbing system of stromboli volcano and hence to forecast the occurrence of phases of higher intensity volcanic activity

uranium mobility in the sediment hosted uranium deposit of coutras france abstract recent mobility of u was investigated in the coutras u deposit gironde france located in lutetian sediments near the surface the coutras deposit is a belt of tabular ore bodies separated into two areas by the dronne river the jean vincent area close to the surface and the le fieu area located at a maximum depth of 100 m the immobility of th is supported by whole rock th contents which do not vary significantly with u content the present hydrological regime in the jean vincent area is characterized by oxidizing waters flowing toward the dronne river activity ratios ar of 230th 234u in rocks which range from 0 55 to 12 demonstrate recent u accumulation and leaching the 234u 238u ar range from 0 94 to 1 52 in the rocks and from 0 94 to 1 61 in the waters recent accumulation of u is favored along redox barriers where mo v se and as are also mobilized waters in the le fieu area are nearly stagnant they are reduced and exhibit a different chemical composition than waters in the jean vincent area with higher contents of ca mg na k cl hco3 po4 ra ba mn higher 234u 238u ar 1 33 4 63 and lower u content the le fieu rock samples do not show any isotopic evidence of recent leaching of u but both relative excesses and deficits of 234u are observed preferential mobility of 234u in the reduced le fieu area is interpreted according to the recoil model the results place new constraints on the model of cowart and osmond and should be useful in prospecting for tabular u deposits in reduced environments

topographic mapping from interferometric synthetic aperture radar observations interferometric synthetic aperture radar observations provide a means for obtaining high resolution topographic terrain maps from data acquired simultaneously at two slightly displaced antennas calculation of the three dimensional coordinates of all the points in a radar image can be made from the combination of along track slant range and interferometer fringe measurements thus the result compensates for the layover exhibited by conventional radar maps and removes the false targets generated by multiple signal paths to a given object in the scene we have derived a topographic map of a portion of the san francisco bay area utilizing data that were recorded by a radar system mounted on a nasa cv990 aircraft and processed by a general purpose digital computer this map displays the height above sea level of a region approximately 11 km by 10 km in size sampled on an 11 m pixel grid uncertainties in the estimated height result from imprecise knowledge of the observational geometry radar bandwidth limitations and finite signal to noise ratios for our system each factor contributed approximately 3 4 m to a relative rms error of about 6 m additional global errors of the order of 10 m can result from inaccurate monitoring of aircraft attitude the statistical variation of the height measurements from the ocean portion of the map which we can presume to be quite flat is 2 10 m rms which is consistent with the theoretical estimate comparison of our results with u s geological survey contour maps indicates a high degree of correlation between the two sets of altitude data

uranium and organic matter in a paleodeltaic environment the coutras deposit gironde france the coutras uranium deposit located north of the aquitaine basin france was discovered by cogema in 1980 it is hosted by middle eocene arenaceous unconsolidated sediments at the surface the jean vincent area and down to 100 m depth the le fieu area the detrital components of the sediments are mainly quartz feldspars and granitic and metamorphic rock fragments the host sediments originated from the french massif central to the east orebodies are black tabular lenses occurring in sediments deposited in a delta plain environment where plant debris is abundant preservation of ligneous vegetation during burial established a reducing environment capable of concentrating uranium there is a good correlation between uranium total sulfur and organic carbon uranium is mainly fixed in organics as organo uranyl compounds uranium minerals detected include coffinite pitchblende and secondary hexavalent u minerals accumulation of uranium was favored by a permeable organic rich and slightly acid environment adsorption processes probably enhanced ore formation the lack of oxidized tongues may be the result of oxygen depleted uranium bearing solutions when they reached the organic rich zone the coutras uranium deposit is then a good example of a tabular type deposit which was deposited during early diagenesis

use of ground penetrating radar for assessment of potential sinkhole conditions an example from ghor al haditha area jordan sinkholes are near surface indicators of active karst features at depth such as cavities conduits and solutionally enlarged fractures this study tests the usefulness of ground penetrating radar gpr to identify and locate buried sinkholes as a means of interpreting the existence of these subsurface hydraulically active karst features gpr survey was made at the ghor al haditha area west of the jordan dstf in the jordan valley escarpment at the eastern dead sea shoreline gpr profiles 100 mhz made along the eastern dead sea shoreline showed a trough like pattern of radar reflections outlining a series of possible filled sinkholes this feature is about 38 m wide and about 12 m deep its width is consistent with the width of the feature obtained from the topographic map of the area the gpr survey suggests that this feature has been filled with relatively dense and resistive materials this structure lies almost directly above a major water bearing zone

cover collapse sinkholes in the tournaisis area southern belgium abstract in the tournaisis area southern belgium cover collapse sinkholes have been reported since the beginning of this century in this area the relatively flat lying carboniferous limestone is overlain by an unconformable mesocenozoic cover recent research has shown that these sinkholes developed from reactivated paleokarsts the intensive pumping for domestic and industrial water supply combined with the dewatering due to deep limestone quarries operations resulted in the lowering of groundwater levels this triggered the reactivation of paleokarstic systems and thus the occurrence of cover collapse sinkholes these sudden and unexpected collapses have already had major impacts in the region in 1977 about thirty sinkholes opened up along the escaut river downstream from the city of tournai as a consequence the groundwater was polluted by an extensive loss of river water into the carboniferous aquifer more recently a house and industrial facilities were severely damaged by such cover collapse sinkholes in this context a geoharzard map would be a valuable tool as far as regional development is concerned this points at the importance to develop methods to locate and characterize hidden paleokarsts a study site has been chosen in an area where sinkholes have been opening up for about ten years a geophysical survey of the site which included electrical resistance mapping of the area has shown weakness lineaments these lineaments are parallel to a main fault affecting the region

redox driven changes in porewater chemistry in the unsaturated zone of the chalk aquifer beneath unlined cattle slurry lagoons farm waste stores such as cattle slurry lagoons are widespread in the uk and many overly important aquifers stores can be serious risks to water quality because they are important sources of n species organic c and pathogenic microbes at two sites on the chalk aquifer of southern england inclined boreholes were drilled and cored to obtain aquifer material from directly beneath unlined slurry stores vertical boreholes were also drilled adjacent to the slurry stores to determine any lateral movement of contaminants interstitial porewaters were analysed for major and minor ions and s isotopes at the second site unsaturated zone gases were sampled from the inclined hole infiltration of slurry into the unsaturated zone caused significantly elevated concentrations of metals such as cu and ni at both sites sulphate reduction was occurring at site 1 as evidenced by so4 concentrations decreasing from 150 to 50 mg l and enhanced ratios of 34s so4 and 18o so4 ammonium n also leaches along with dissolved organic c which were found 17 m below ground surface at concentrations up to 400 and 260 mg l respectively contaminant concentrations were similar in the porewaters from both the inclined and vertical boreholes at site 2 higher contaminant concentrations were found in the inclined borehole compared with the vertical borehole organic c concentrations were considerably lower than at site 1 ranging from 10 to 70 mg l ammonium n concentrations reached a maximum concentration of 25 mg l however no3 n concentrations were up to 500 mg l and so4 concentrations were generally higher than site 1 data for n2 ar and 15n n2 from the gas samplers show a peak of 102 and 2 2 respectively at 14 m below ground level indicating denitrification was taking place evidence from 34s so4 and 18o so4 suggest that some so4 reduction was taking place simultaneously from ch4 and nh3 detected at depth it is suggested that slurry contamination emanating from early use of the store has passed through the top 18 m of the unsaturated zone at site 2 the presence of high concentrations of no3 and lower concentrations of organic c suggests that this lagoon has formed a relatively impermeable seal at its base within the first few years of its lifetime the anoxic conditions at both sites may have mobilised u from n p k fertilisers both sites are continuing to impact on the porewater chemistry and pose a risk of groundwater contamination

responses of cover collapse sinkholes to groundwater changes a case study of early warning of soil cave and sinkhole activity on datansha island in guangzhou china in karst areas of quaternary sediments fissures and solution channels through soluble rocks provide unseen conduits for the vertical movement of surface water into the underlying karst aquifers this downward flow may also transport overburden material which can result in the formation of soil caves and ground loss called cover collapse sinkholes because of the concealed development of such soil caves and generally complicated geological conditions the prediction of soil cave development and sinkhole activity is far from perfect this study focused on the early warning of soil cave and sinkhole development by monitoring groundwater level decline based on the improved terzaghi loosening pressure theory and using excess pore water pressure two types of critical groundwater level decline are discussed the first denoted as 0 is the critical groundwater level decline related to soil cave formation and evolution the second denoted as ht is the critical groundwater level decline related to soil cave roof collapse this method of groundwater monitoring for the early warning of soil cave and sinkhole development is currently being applied on datansha island in guangzhou china

rapid subsidence in damaging sinkholes measurement by high precision leveling and the role of salt dissolution abstract investigations dealing with subsidence monitoring in active sinkholes are very scarce especially when compared with other ground instability phenomena like landslides this is largely related to the catastrophic behaviour that typifies most sinkholes in carbonate karst areas active subsidence in five sinkholes up to ca 500 m across has been quantitatively characterised by means of high precision differential leveling the sinkholes occur on poorly indurated alluvium underlain by salt bearing evaporites and cause severe damage on various human structures the leveling data have provided accurate information on multiple features of the subsidence phenomena with practical implications 1 precise location of the vaguely defined edges of the subsidence zones and their spatial relationships with surveyed surface deformation features 2 spatial deformation patterns and relative contribution of subsidence mechanisms sagging versus collapse 3 accurate subsidence rates and their spatial variability with maximum and mean vertical displacement rates ranging from 1 0 to 11 8 cm yr and 1 9 to 26 1 cm yr respectively 4 identification of sinkholes that experience continuous subsidence at constant rates or with significant temporal changes and 5 rates of volumetric surface changes as an approximation to rates of dissolution induced volumetric depletion in the subsurface reaching as much as 10 900 m3 yr in the largest sinkhole the high subsidence rates as well as the annual volumetric changes are attributed to rapid dissolution of high solubility salts

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

isotopic composition of sulfate as a tracer of natural and anthropogenic influences on groundwater geochemistry in an urban sandstone aquifer birmingham uk abstract development and management of urban groundwater resources is limited in practice by a lack of knowledge of the nature distribution and sources of groundwater contamination in an urban aquifer that may have had complex land use and abstraction history sulfate is associated with many of the solute sources to urban groundwater and in this study the use of dual isotope 18o and 34s fingerprinting of so 4 2 in groundwater to assess the contribution of different sources to urban groundwater is investigated groundwater 70 locations and surface water samples from the city of birmingham on the triassic sherwood sandstone aquifer have been analyzed for inorganic chemical and so 4 2 isotopic composition isotopic compositions of so 4 2 associated with various solute sources have also been determined sulfate derived from pyrite oxidation during recharge through quaternary drift deposits is characteristically depleted in 18o and 34s compared to other sources and is ubiquitous in unconfined zone groundwater though the contribution from this source has increased markedly following draw down induced by abstraction from the aquifer in unpolluted groundwaters other so 4 2 sources are dissolution of evaporite minerals confined zone and rainfall unconfined zone unfortunately so 4 2 isotopic composition cannot distinguish between made ground i e artificial man made ground usually demolition waste and sewage sources of so 4 2 which constitute the major contributions to so 4 2 in polluted urban groundwater at most sites contributions of so 4 2 from spilt industrial acids do have a distinctive isotopic composition seen at many metal working and former metal working sites estimates of solute contributions derived from these sources derived in this way provide a useful check on the calibration of aquifer and pollutant flux recharge models for urban groundwater

sinkhole investigation in an urban area by trenching in combination with gpr ert and high precision leveling mantled evaporite karst of zaragoza city ne spain abstract sinkhole risks are becoming particularly severe in urban areas that lack careful planning and where karst depressions are frequently filled and developed these built up areas are the most challenging for sinkhole investigation they are the ones that require the highest priority and the application of novel approaches aimed at reducing the epistemic uncertainties associated with hazard assessments this work illustrates the strengths of the rarely used trenching technique for the investigation of sinkholes in mantled karst areas the approach has been tested on a buried sinkhole in the evaporite karst of zaragoza city analysing and comparing data gathered by trenching ground penetrating radar gpr using shielded and unshielded antennas with different frequencies electrical resistivity tomography ert and high precision leveling the sinkhole is located beneath a street and has led to the demolition of buildings creating a risk situation that requires careful assessment and management trenching provided the largest amount of objective data required for hazard assessment 1 precise location of the sinkhole edges 2 internal structure cumulative displacement subsidence mechanisms and their contribution the trench exposed an asymmetric structure with a minimum vertical displacement of 6 2 m comprising a complex collapse with different generations of faults and two marginal zones affected by gentle inward tilting collapse faulting accommodates at least 70 of the subsidence 3 age of the sinkhole and average subsidence rate the sinkhole was initiated sometime before or within 337 435 cal yr ad indicating a long term subsidence rate of ca 3 7 4 2 mm yr 4 kinematic style characterised by episodic collapse events as supported by leveling data the retrodeformation analysis together with geochronological data indicates four collapse events with a recurrence of around 400 years and suggests enhanced activity since ca 1950 ad the performance of gpr was highly variable depending mainly on the type of antenna and the timing of data acquisition the best quality data were obtained with shielded antennas and during relatively drier conditions the rather poor performance of ert commonly an adequate method for resolving subsidence structures at depth is attributed to the complex structure of the collapse sinkhole with spatially dense and abrupt resistivity changes in resistivity this case study strongly substantiates the implementation of the relatively inexpensive and highly objective trenching technique in sinkhole investigations

subsidence and sinkhole hazard assessment in the southern dead sea area jordan the dead sea area is increasingly facing serious subsidence and sinkhole hazards on march 22 2000 the dyke of a two month old major salt evaporation pond located along the shore of the lisan peninsula jordan collapsed over almost two kilometers the pond was set up over unstable new lands that have been progressively emerging during the last three decades in one hour 56 millions m 3 of brine poured out into the northern natural part of the sea here we present data suggesting that the drop of the water level in conjunction with the particular tectonic setting of this area is at least one of the factors that led to the disaster we focused our study over the northern part of the lisan peninsula and ghor al haditha which are two places undergoing the most intense deformations along the jordanian dead sea coast we used the results of a static high precision gravimetric survey to detect subsurface cavities in ghor al haditha we analyzed a interferometric digital terrain model of the recent emerged platform of the lisan peninsula and interpreted radar differential interferograms contemporary with gravity measurements for the peninsula we discuss the possibilities to detect assess and monitor areas prone to collapse on the jordanian side of the southern dead sea coast

sinkholes subsidence and subrosion on the eastern shore of the dead sea as revealed by a close range photogrammetric survey abstract ground subsidence and sinkhole collapse are phenomena affecting regions of karst geology worldwide the rapid development of such phenomena around the dead sea in the last four decades poses a major geological hazard to the local population agriculture and industry nonetheless many aspects of this hazard are still incompletely described and understood especially on the eastern dead sea shore in this work we present a first low altitude our analysis reveals a kilometer scale sinuous depression bound partly by flexure and partly by non tectonic faults the estimated minimum volume loss of this subsided zone is 1 83 106 m3 with an average subsidence rate of 0 21 m yr 1 over the last 25 years sinkholes in the surveyed area are localized mainly within this depression the sinkholes are commonly elliptically shaped mean eccentricity 1 31 and clustered nearest neighbor ratio 0 69 their morphologies and orientations depend on the type of sediment they form in in mud sinkholes have a low depth to diameter ratio 0 14 and a long axis azimuth of nne ne in alluvium sinkholes have a higher ratio 0 4 and are orientated nnw n from field work we identify actively evolving artesian springs and channelized sediment laden groundwater flows that appear locally in the main depression consequently subrosion i e subsurface mechanical erosion is identified as a key physical process in addition to dissolution behind the subsidence and sinkhole hazard furthermore satellite image analysis links the development of the sinuous depression and sinkhole formation at ghor al haditha to preferential groundwater flow paths along ancient and current wadi riverbeds