the sinkhole of doganella pontina plain central italy a case study describes the recent catastrophic subsidence of the land surface neighboring the lepini karstic range lazio region a number of sinkholes in the pontina plain are shown on the early topographic maps dated 1850 their origin is natural and related to subsidence that occurred during the holocene a review of sinkholes in central italy was made by facenna and others 1993 the aim of this study is to clarify the possible relationships between tectonics and sinkhole formation the subsidence phenomena have been related to the slow dissolution of the buried carbonate bedrock due to fluids rich in co2 h2s and so2 which migrate through major tectonic fractures lowering of piezometric levels in waterbearing formations and seismic events are also important factors as they may upset the stability of a cave system buried by unconsolidated deposits

mechanics of upward propagation of cover collapse sinkholes cover collapse sinkholes occur by failure of the walls of a soil void above cavernous bedrock i examine conditions for failure in compression by crack propagation and coalescence and for failure by sloughing in which pore water pressure produces a net tension perpendicular to the wall of the void compressive failure without relaxation of stress does not explain observed long term stability of thick soils nor failures in thin residual soils if stress relaxation occurs with compressive failure soil voids tend to stabilize and sinkholes are not predicted sloughing failure is not predicted for steady state pore pressure fields even for a perched water table at the surface over a drained void transient pore pressure conditions that could produce sloughing may result from 1 rapid drawdown causing soil consolidation and transient high pore pressure gradients 2 approach of a wetting front in unsaturated soil with high permeability behind the front 3 dissolution of air from bubbles in the soil and exsolution near the void producing a low permeability zone near the void

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

fracture controlled fluid circulation and dissolutional weathering in sinkhole prone carbonate rocks from central italy abstract fractures karstic cavities and calcite precipitates are analysed on mesozoic carbonate strata from the cornicolani mountains central italy to quantify the relationships between fractures and related karstic cavities and to infer the fracture controlled fluid pathways the study area is characterized by active sinkholes and other karstic caves which are among the deepest ones in the world results show a clear control of fractures on the process of dissolutional weathering and therefore on the fluid circulation a model is proposed in which two different modes of dissolutional weathering coexist i a mode of diffuse weathering consisting in the dissolutional enlargement of closely spaced joints and bedding surfaces this process affects the strata situated at depths of up to 5 m ii a mode of more concentrated weathering active along highly permeable fault damage zones at depths of at least 70 m these processes are mostly connected with the shallow circulation of calcite dissolving meteoric waters and are controlled by the disparity of permeability between the fault damage zones and the surrounding jointed strata some calcite precipitates along the studied fault damage zones may be connected with a dissolutional process operated by waters that interacted with the adjacent quiescent volcanic district such calcite dissolving waters and the presence of high permeable fault damage zones along which the waters may ascent are probably the cause for the development of some of the deep sinkholes along faults in the study area

groundwater fluxes into a submerged sinkhole area central italy using radon and water chemistry abstract the groundwater contribution into green lake and black lake vescovo lakes group two cover collapse sinkholes in pontina plain central italy was estimated using water chemistry and a 222 rn budget these data can constrain the interactions between sinkholes and deep seated fluid circulation with a special focus on the possibility of the bedrock karst aquifer feeding the lake the rn budget accounted for all quantifiable surface and subsurface input and output fluxes including the flux across the sediment water interface the total value of groundwater discharge into green lake and black lake 540 160 l s 1 obtained from the rn budget is lower than but comparable with historical data on the springs group discharge estimated in the same period of the year 800 90 l s 1 besides being an indirect test for the reliability of the rn budget tool it confirms that both green and black lake are effectively springs and not simply water filled sinkholes new data on the water chemistry and the groundwater fluxes into the sinkhole area of vescovo lakes allows the assessment of the mechanism responsible for sinkhole formation in pontina plain and suggests the necessity of monitoring the changes of physical and chemical parameters of groundwater below the plain in order to mitigate the associated risk

extrusion vs accretion at the frictional viscous decollement transition in experimental thrust wedges the role of convergence velocity in many cases thrust wedges accreted at shallow crustal levels show an across strike rheological variability along the basal decollement notably from brittle to ductile behaviour in this paper we illustrate the results of sandbox analogue modelling research devoted to studying the influence of convergence velocity on wedge architecture when laterally juxtaposed frictional and viscous materials occur along the basal decolle ment of accreting thrust wedges our results show that slow convergence favours a near symmetrical distribution of thrust vergence within wedge sectors accreted above viscous decoll ement material whereas fast convergence favours vergence asymmetry in particular at fast convergence rates the hinter landward extrusion of viscous decollement material at the toe of the frictional wedge is favoured and contributed to accommodate a significant amount of the total contraction

earth fissures triggered by groundwater withdrawal and coupled by geological structures in jiangsu province china earth fissures in jiangsu province china have caused serious damages to properties farmlands and infrastructures and adversely affected the local or regional economic development under the geological and environmental background in jiangsu province this paper presents the earth fissures caused by excessive groundwater withdrawal and coupled by distinctive geological structures such as ancient yellow river fault in xuzhou karst area and ancient yangtze river course and bedrock hills in suzhou wuxi and changzhou area although all the earth fissures are triggered by groundwater exploitation the characteristics are strongly affected by the specific geological and hydrogeological settings in particular in the water thirsty xuzhou city the cone of depression caused by groundwater extraction enlarged nearly 20 times and the piezometric head of groundwater declined 17 m over a decade as groundwater is extracted from the shallowly buried karst strata in the ancient yellow river fault zone the development of earth fissures is highly associated with the development of karstic cavities and sinkholes and their distribution is controlled by the ancient yellow river fault with all the 17 sinkholes on the fault on the other hand in the rapidly developing southern jiangsu province groundwater is mainly pumped from the second confined aquifer in the quaternary which is distributed neither homogeneously nor isotropically the second confined aquifer comprises more than 50 m thick sand over the ancient yangtze river course but this layer may completely miss on the riverbank and bedrock hills with a typical drawdown rate of 4 6 m per annum the piezometric head of groundwater in the second confined aquifer has declined 76 m at maocunyuan since 1970s and 40 m at changjing since mid 1980s and a large land subsidence e g 1 100 mm at maocunyuan is triggered coupled with the dramatic change of the bedrock topography that was revealed through traditional geological drilling and modern seismic reflection methods the geological structure controlled differential settlement and earth fissures are phenomenal in this area

simulation experiment on sinkhole formation caused by soils disintegration and the advance forecasting of sinkhole risk sinkholes are a common geological hazard around the world however it is difficult to carry out the associated indoor simulation experiments because of the complicated factors involved our previous research showed that sinkholes in the aerated zone caused by soil disintegration exhibit accurate critical conditions therefore the kind of sinkhole formation is simulated in the paper before the simulate experiment the critical value of the disintegration of clay samples is tested which helps to control the simulation conditions with a designed simulation apparatus soil disintegration was conducted 70 times from october 23 2017 to june 1 2018 and a sinkhole formed this experiment results indicate two developmental laws of sinkholes forming in the aerated zone one is the forming process which has three stages soil void formation soil void expansion and roof collapse second is that the two conditions water content is less than the critical value and contact between water and soil causing the sinkhole formation at the forming two conditions are clear and can easily be monitored by the associated factors in the field where sinkholes have occurred or are about to occur according to the principle another simulation experiment was carried out as a result an advanced prediction of a sinkhole is achieved in the aerated zone

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

biomarker hydrogen isotope composition δd as proxy for holocene hydroclimatic change and seismic activity in sw peloponnese greece we present a 6000 year long record tracing hydroclimate changes in sw greece based on hydrogen isotope composition of aquatic plant derived n c 23 alkanes d c23 in a sediment core from the messe

detection of preferential infiltration pathways in sinkholes using joint inversion of self potential and em 34 conductivity data the percolation of water in the ground is responsible for measurable electric potentials called self potentials these potentials are influenced by the distribution of the electrical conductivity of the ground because sinkholes are associated both with self potential and electrical conductivity anomalies a joint inversion of em 34 conductivity and self potential data is proposed as a way of delineating the location of these features self potential and em conductivity data were obtained at a test site in normandy france where sinkholes and crypto sinkholes are present over a karstic area in a chalk substratum overlain by clay with flint and loess covers the presence of sinkholes and crypto sinkholes is associated with negative self potential anomalies with respect to a reference electrode located outside the area where the sinkholes are clustered the sinkholes also have a conductivity signature identified by the em 34 conductivity data we used the simulated annealing method which is a global optimization technique to invert jointly em 34 conductivity and self potential data self potential and electrical conductivity provide clear complementary information to determine the interface between the loess and clay with flint formations the sinkholes and crypto sinkholes are marked by depressions in this interface focusing the groundwater flow towards the aquifer contained in the chalk substratum

interaction between shallow and deep aquifers in the tivoli plain central italy enhanced by groundwater extraction a multi isotope approach and geochemical modeling abstract in the tivoli plain rome central italy the interaction between shallow and deep groundwater flow systems enhanced by groundwater extraction has been investigated using isotopic and chemical tracers a conceptual model of the groundwater flowpaths has been developed and verified by geochemical modeling a combined hydrogeochemical and isotopic investigation using ion relationships such as dic cl ca ca mg so 4 so 4 hco 3 and environmental isotopes 18 o 2 h 87 sr 86 sr 34 s and 13 c was carried out in order to determine the sources of recharge of the aquifer the origin of solutes and the mixing processes in groundwater of tivoli plain multivariate statistical methods such as principal component analysis and cluster analyses have confirmed the existence of different geochemical facies and the role of mixing in the chemical composition of the groundwater results indicate that the hydrochemistry of groundwater is characterized by mixing between end members coming directly from carbonate recharge areas and to groundwater circulating in a deeply buried meso cenozoic carbonate sequence the travertine aquifer is fed by both flow systems but a local contribution by direct input in the plain has also been recognized the stable isotope data 18 o 2 h 13 c and 34 s supports the flow system conceptual model inferred from the geochemical data and represents key data to quantify the geochemical mixing in the different groundwaters of the plain the results of numerical modeling phreeqc are consistent with the flowpaths derived from the hydrogeochemical conceptual model the inverse models performed generated the main geochemical processes occurring in the groundwater flow system which also included mixing geochemical and isotope modeling demonstrate an increasing influence of groundwater from the deeply buried aquifer in the travertine aquifer enhanced by lowering of the travertine aquifer water table due to quarry pumping

characterizing hydrological processes on loess slopes using electrical resistivity tomography a case study of the heifangtai terrace northwest china abstract from the perspective of engineering geology loess has long been considered as a homogeneous and porous material it is commonly believed that water penetrates loess via pores and in some cases causing mass movements however several researchers have expressed doubts about this mechanism as a cause of slope failures in loess and moreover the actual hydrological processes operating in loess deposits and their effect on slope failures have not been fully investigated here we present the results of an electrical resistivity survey of the heifangtai loess terrace in northwestern china designed to characterize the hydrological processes in loess slopes and their relationship with slope failures the heifangtai loess terrace is located on the fourth terrace of the yellow river and consists of 57 m thickness of aeolian loess 2d and 3d electrical resistivity tomography ert was used to monitor the movement of ground water before and after irrigation and rainfall events and the evolution of a sink hole in the toe of the landslide deposits our main findings are as follows 1 based on the 2d ert results the depth of infiltration into the thick unsaturated loess is not more than 5 m in the profile at the top of the landslide 2 electrical resistivity decreased as a result of water infiltration through sinkholes and this process can increase the soil water content and induce soil liquefaction which can eventually result in land sliding 3 landslide deposits block the groundwater drainage channels through the loess which results in the concentration of water in the toe of the landslide consequently groundwater together with rainfall triggers the failure of sinkholes or cracks which may induce a continuing process of new slope failures at the sites of past landslide

a late cretaceous polygonal fault system in central north america polygonal fault systems pfs have been interpreted worldwide using seismic data imaging sedimentary strata normal faults initiate over a large area in fine grained subaqueous strata soon after deposition as they continue to grow laterally and vertically their fault traces intersect to form polygons in plan view these polygons are difficult to image without three dimensional 3 d seismic data the faulting is initiated during sediment dewatering and mud particle consolidation that can be independent of external stresses in the past 20 years hundreds of basins worldwide have been interpreted to contain polygonal faults this paper presents a pfs interpretation for fine grained sediments deposited in the late cretaceous western interior seaway of the great plains of north america the faulted strata have been observed as a pfs at depths ranging from 2750 m subsurface to outcrop seismic dataset interpretations and borehole analyses corroborate previously published outcrop analyses and seismic interpretations the larger observed faults are mesoscale in size with throws up to 80 m and strike lengths up to 1 5 km potentially encompassing over 2 000 000 km 2 observational averages imply 10 7 or more mesoscale size faults with an order of magnitude greater number of smaller faults at shallow depth and outcrop the pfs model of extensive normal faulting could help to explain late cretaceous shale faulting attributed to other causes such as deeper sediment dissolution or glacial processes in the subsurface faulting and fracturing consistent with a pfs model can help to explain fault geometries observed in well control and 3 d seismic data

the romeriksporten railway tunnel drainage effects on peatlands in the lake northern puttjern area this study presents the results of an investigation of drainage effects of the romeriksporten railway tunnel on peatlands in the lake northern puttjern area drainage impacts on peatlands occurred in marked depressions reflecting faults or weakness zones in bedrocks the impacts were most evident near the tunnel trace but dry peatlands and streams were observed as far as 600 m from the tunnel trace several types of drainage effects were observed on peatland surfaces after tunnelling surface subsidence and formation of local depressions peat slides peat cracking dry peat holes and death of vegetation the effects depended clearly on peatland properties the greatest and most damaging effects were associated with thick peat layers around open water surface here lowering of the water table caused peat slides such areas will generally be extremely vulnerable to lowering of the water level the magnitude of subsidence of peatlands depends on peat thickness peat decomposition and groundwater lowering even after seven years with artificial infiltration in bedrock wells in dry periods to counteract water table lowering peat subsidence and peat slides were evident demonstrating that temporary draw down of water can result in irreversible impacts on peatlands to better be able to avoid damaging effects of tunnel drainage on environment investigations of properties of peatlands above possible tunnel traces should be integrated in the planning procedure for tunnel constructions in mires above such traces the occurrence of floating peat mats degree of peat decomposition peat thickness deliveries of water from surrounding catchments in dry periods and possible pathways of leakage through subsoils and bedrocks should be examined as basis for assessment of vulnerability of peatlands to tunnel drainage and selection of tunnel traces that evade the most vulnerable peatlands when such areas can not be avoided requirements should be set to the tightening of the tunnel to prevent damaging water draw downs in dry periods observations of drainage effects on peatland surfaces can complement hydrological information from measurements of tunnel leakages and groundwater levels and thus contribute to provide a broader picture of hydrological impacts and bedrock hydrogeology

on the value of dolines in gypsum terrains as a geological heritage an example from sivas basin turkey karst topography is a landscape shaped by the dissolution of a layer or layers of soluble bedrock usually limestone and evaporites karstification in the sivas basin turkey has sculpted a beautiful landscape with a distinctive beauty and appeal for both local inhabitants and visitors dolines are very special geological landscape features found in karst regions and the sivas basin has several giant dolines amongst its thousands of smaller dolines the basin constitutes a distinctive karst architecture with a system of collapse and or dolines and caves anyone who walks along the shores of a lake resulting from the collapse in this gypsum terrain will be amazed with the lake and rocks that surround them in this paper dolines in the gypsum terrain are evaluated and discussed according to their value as a geological heritage three main characteristics of dolines namely their scientific aesthetic and ecosystem importance are considered and discussed dolines and karstified areas as representative examples of landform types possess the three attributes for them to be considered as a geological heritage in that they demonstrate the effect of erosion on the landform geomorphic processes that are still active and a range of features characteristic of the rock unit involved

sagging and collapse sinkholes over hypogenic hydrothermal karst in a carbonate terrain abstract we show that clusters of karst sinkholes can occur on carbonate hypogene karst terrains unlike common doline karst of dissolution origin the studied sinkholes form mainly by sagging and collapse thermal survey osl dating and morphologic analysis during quarrying and excavations are applied to study the sinkholes at the ayyalon karst israel the thermal survey shows the spatial pattern of rising warm water plumes whose temperature is 2 c warmer than the surrounding aquifer water these plumes dissolve the limestone creating large voids and maze caves mass wasting forms surface sinkholes mainly by sagging and collapse both types of deformation often occur within the same depression lack of hydrologic connection between the surface and underground voids constrain drainage and promote rapid accumulation of colluvium dust and pedogenic clays these have filled the sinkholes up to their rim before the late holocene osl dating constrains the rate of sediment accumulation within the sinkholes the average filling rate thickness divided by elapsed time is 47 mm ka 1 for the last 53 4 ka in sinkhole 1 while in sinkhole 2 nesher ramla karst depression the rate is 61 mm ka 1 from 200 to 78 ka and 173 mm ka 1 since 78 ka between 170 and 78 ka sinkhole 2 was intensively used by middle paleolithic hominins the studied sinkholes may be considered as a type locality for hypogene sinkhole terrain on carbonate rocks

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

groundwater mixing in the discharge area of san vittorino plain central italy geochemical characterization and implication for drinking uses discharge areas of carbonate fractured and karstified aquifers are a sensitive system of great interest where frequently groundwater resources are tapped for drinking water supply in geological settings affected by recent and or active tectonics mixing between fresh water coming from recharge areas and groundwater from deeper circuits influenced by raising fluids influences hydrogeochemistry surveys on major ions trace elements and stable isotopes have been performed in the san vittorino plain central italy where the major source of drinking water for rome is located peschiera springs mean discharge 18 m3 s 1 half of them tapped results of 21 springs revealed different contribution from recharge areas and deep flow paths by increasing salinity and ion content with particular references to ca2 hco3 and so4 2 three main groups respectively related to fresh waters from recharge areas groundwater from deep contribution and a mixing group between them have been identified water stable isotopes allow to identify the common origin from rainfall and a very steady contribution with seasons and year due to the huge extent of recharge area 1000 km2 saturation indexes gave insight on the contribution of deep fluids mainly co2 and h2s which turned groundwater to undersaturated conditions facilitating rock dissolution by phreeqc software the mixing between two considered end members has been simulated evaluating about 25 of deep contribution in the basal springs of san vittorino plain chemistry of peschiera spring reveals a very limited percentage of deep flow paths 10 which can lead to slight hydrochemistry changes even in possible drought conditions when discharge can decrease until 15 m3 s 1

new insights into the genesis of the miocene collapse structures of the island of gozo malta central mediterranean sea the large palaeosinkholes located in the nw of gozo central mediterranean sea malta offer excellent exposures that provide information on the geometry and kinematics of large karst related collapse structures detailed geological analysis of these peculiar palaeosinkholes indicates that deep seated evaporite dissolution is the most feasible hypothesis to explain their formation according to the following evidence 1 several structures have been formed by progressive foundering of cylindrical blocks with limited internal deformation as revealed by the synsedimentary subsidence recorded by their miocene sedimentary fill this subsidence mechanism is more compatible with interstratal dissolution of evaporites than karstification and cave development in limestone formations 2 the dimensions and deformation style of the palaeosinkholes are similar to those of other collapse structures related to deep seated dissolution of salt bearing evaporites 3 the arcuate monocline associated with some of these collapse structures is also a characteristic feature of subsidence related to dissolution of evaporites however no major evaporite formations have been documented so far in the subsurface of the malta platform supplementary material detailed descriptions of the collapse structures of the island of gozo malta central mediterranean sea are available at www geolsoc org uk sup18808

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

giant solution subsidence structure in the western mediterranean related to deep substratum dissolution terra nova 24 181 188 2012 abstract sinkholes are frequently observed where soluble rocks are present in meteoritic recharge areas or when subsurface dissolution causes ground collapse seismic profiles on the inner shelf of the gulf of lions w mediterranean display a giant atypical sub circular structure up to 800 m thick and 2 km wide it is characterized by down warped internal seismic reflections forming a concave v shaped depression rooted in the substratum most likely carbonated this structure is interpreted as a poly phased solution subsidence collapse structure of plio quaternary age the last phase of deformation probably occurred during the last sea level low stand phase the mechanism proposed for the creation of this structure is collapse dissolution of the soluble substratum as a result of a combination of several possible factors including pre existing deep messinian palaeo karst with active groundwater flows during plio quaternary lowstands and deep rooted acidic fluids ascending through the substratum