Sinkhole

Conventional 2D electrical resistivity tomography (ERT) data were acquired along 16 parallel traverses spaced at 6.1 m (20 ft) intervals across a karst sinkhole site in Greene County Missouri. The acquired ERT data were processed as both 2D data and pseudo-3D data. Based on the correlation with the available core hole control, multichannel analysis of surface waves (MASW) data and field observations, it is concluded that the subsurface structure of the sinkhole is more reliably imaged on the pseudo-3D dataset than in the 2D dataset. The interpretation results of the pseudo-3D ERT indicated that the sinkhole developed at the intersection of three vertical solution-widened joint sets.

Dolines are regularly referred as diagnostic karst landforms, as their formation is usually attributed to chemical weathering or dissolution, which is the most typical karst process. In this paper, we re-evaluate the formation of the two most typical dissolution dolines,
provided by Cvijić. Within this study, we stated that both cases, which constitute the
foundations of interpretation of dissolution dolines formation, are actually not caused by dissolution of the surface. The purpose of the article is to provide a doubt about the understanding of formation of the most common karst landform.

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.

This work describes the fossil accumulations recovered during the excavation of the sinkhole called Sima de Abraham (Sierra Alcaide, Priego de Córdoba, Iberia). This site is characterized by a prominent accumulation of mammalian fossil remains, including carnivores (especially bears, lynx, wildcats and spotted hyenas) and artiodactyls (red deer and ibex) among other species. Human activity does not seem to be the primary agent of accumulation, although a series of cut marks have been found on the articular cavity of the proximal ulna of a large bear, providing interesting insight into the interaction between bears and humans. The age of the deposit was set in the Late Pleistocene in a previous study according to the presence of the southern water vole (Arvicola sapidus) and subsequently corroborated by means of AMS and U/Th, obtaining an approximate age of 40- 30 ky BP, corresponding to MIS 3, in the latest Pleistocene.

The main focus of this paper is to use 3D analysis to investigate sinkhole formation behavior. This is completed by analysing different square sinkhole cavity opening sizes and overburden properties with trapdoor analysis. The research is conducted by closely examining sinkhole structures through finite difference software FLAC 3D. Once the cavity trapdoor roof is released, the effect of the trapdoor on the overbuden of the sinkhole can be analysed. The sinkholes models are computed via the strength reduction method, which can produce the factor of safety of the formation along with the final overburden displacements and sinkhole shape. The completion of 3D numerical models allows for numerous sinkhole simulations, with varying material properties and different overburden depth to cavity width ratios. It is expected that this research would increase the understanding of the phenomena of sinkholes by making use of three dimensional numerical simulations.

Gypsum karst problems in the Permian and Triassic sequences of England have caused difficult conditions for bridge and road construction. In Northern England, the Ripon Bypass crosses Permian strata affected by active gypsum karst and severe subsidence problems. Here, the initial borehole site investigation for the road was supplemented by resistivity tomography studies. The roadway was reinforced with two layers of tensile membrane material within the earth embankment. This will prevent dangerous catastrophic collapse, but will allow sagging to show where problems exist. The River Ure Bridge was constructed across an area of subsidence pipes filled with alluvial deposits. It was built with extra strength, larger than normal foundations. If one pier fails, the bridge is designed for adjacent arches to span the gap without collapse. The bridge piers are also fitted with electronic load monitoring to warn of failure. In the Midlands area of England, road construction over Triassic gypsum has required a phase of ground improvement on the Derby Southern Bypass. Here, the gypsum caps a hill where it was formerly mined; it dips through a karstic dissolution zone into an area of complete dissolution and collapse. The road and an associated flyover were built across these ground conditions. A major grouting program before the earthworks began treated the cavities in the mine workings and the cavernous margin of the gypsum mass. Within the karstic dissolution zone, gypsum blocks and cavities along the route were identified by conductivity and resistivity geophysical surveys, excavated and backfilled. In the areas of complete dissolution and collapse, the road foundation was strengthened with vibrated stone columns and a reinforced concrete road deck was used.

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This essay investigates the formal affinities of the GIF and the sinkhole, asking both why the GIF is one of today’s preferred means of visually engaging the sinkhole and why GIFness can be found foreshadowed in the sinkhole's predigital depictions.

The 2-D distinct element method (DEM) code (PFC2D_V5) is used here to simulate the evolution of subsidence-related karst landforms, such as single and clustered sinkholes, and associated larger-scale depressions. Sub-surface material in the DEM model is removed progressively to produce an array of cavities; this simulates a network of subsurface groundwater conduits growing by chem-ical/mechanical erosion. The growth of the cavity array is coupled mechanically to the gravitationally loaded surroundings , such that cavities can grow also in part by material failure at their margins, which in the limit can produce individual collapse sinkholes. Two end-member growth scenarios of the cavity array and their impact on surface subsidence were examined in the models: (1) cavity growth at the same depth level and growth rate; (2) cavity growth at progressively deepening levels with varying growth rates. These growth scenarios are characterised by differing stress patterns across the cavity array and its overburden, which are in turn an important factor for the formation of sinkholes and uvala-like depressions. For growth scenario (1), a stable compression arch is established around the entire cavity array, hindering sinkhole collapse into individual cavities and favouring block-wise, relatively even subsidence across the whole cavity array. In contrast, for growth scenario (2), the stress system is more heterogeneous, such that local stress concentrations exist around individual cavities, leading to stress interactions and local wall/overburden fractures. Consequently, sinkhole collapses occur in individual cavities, which results in uneven, differential subsidence within a larger-scale depression. Depending on material properties of the cavity-hosting material and the overburden, the larger-scale depression forms either by sinkhole coalescence or by widespread subsidence linked geometrically to the entire cavity array. The results from models with growth scenario (2) are in close agreement with surface morphological and subsurface geo-physical observations from an evaporite karst area on the eastern shore of the Dead Sea.

Sinkholes are commonly defined as deep pits giving the appearance of a chimney or well resulting by collapsing of underground rivers in horizontal or near-bedded lime stones or active cave ceilings. Sinkholes appear as deep pits in the so-called karst land, usually on limestones and carbonates that are easily rinsed with water. The sinkhole occurrences in our country are very often seen on the Obruk Plateau in the Konya Closed Basin. In Karapinar region and its surroundings located in this plateau, especially in recent years surface deformations and sinkhole formations are frequent. The resulting sinkholes in the field of agriculture and occurred in areas close to residential areas is to upset the locals. Several studies have been carried out about the formation of sinkholes in Konya Closed Basin and especially around Karapinar. As a result of the literature survey, different information about the number of sinkholes in the region has been reached. Therefore, an inventory information system that is as up-to-date as daily, accurate, and rich in attribute information (position information, shape, diameter, depth, distance to settlements, year of formation, region etc.), has been created as a result of detailed field work, analyzing satellite images, and examining digital terrain model. The inventory information of the 283 objects created within the scope of the study will be used as support data in the future hazard, risk and planning studies. In addition, the inventory data will be shared through a Web-based system with the relevant people and institutions. The Geoinformation System-like Web application is built using Google Maps and Fusion Tables services for data storage and management, both are free services from Google Inc. The web application's infrastructure includes HTML5, CSS3, JavaScript, Google Maps API V3, and Google Fusion Tables API technologies. Using these technologies, it is possible to create effective map "Mash-Up" applications by adding Google maps to a Web page, where spatial data is stored in Fusion Tables and can be displayed as a layer on Google maps. The sinkhole inventory information system presented with w eb-based application is handled in detail in this article. Görsel Obruk Envanter Bilgi Sistemi için Web Tabanlı Servis Uygulaması; Konya Kapalı Havzası Örnek Çalışması ÖZ: Obruk, yatay veya yataya yakın tabakalı kireç taşlarında bulunan yeraltı nehirlerinin veya aktif mağara tavanlarının çökmesi sonucu oluşmuş , baca veya kuyu görüntüsü veren derin çukurluklara verilen isimdir. Obruklar karst arazi denilen, genelde suyun kolayca eritebildiği kireçtaşları ve karbonatlar içeren düzlüklerde bulunan derin çukurlar şeklinde görünürler. Ülkemizde obruk oluşumları, Konya Kapalı Havzası'nda yer alan Obruk Platosunda çok sıklıkla görülmektedir. Bu

This work deals with the creation of a sinkholes database for the Jordanian coast of the Dead Sea, Ghor Al Haditha area. Ground collapses inventories were carried out between 1991 and 2012. The lineament is replaced and analyzed in its structural setting at regional and local scales. Its direction (N 24 E) is sub-parallel to the ones displayed by most published focal mechanisms in that zone especially the one associated to the 23rd April 1979 earthquake (Mb = 5.1; N 20 E - 5 deg, Arieh et al 1982), which is representative of all focal mechanisms calculated on a fault plane compatible with the general direction of the Jordan - Dead Sea Transform fault system for the east coast of the Dead Sea area. The alignment of sinkholes is constituted by thirteen minor linear segments separated by as many empty spaces. Their organization suggests the existence of a rotational effect caused by stress between two parallel strike-slip faults. Four minor linear units present an en-echelon arrangement from which one can deduce the presence of a local extensional stress field. In this context, sinkholes locations provide information of subsurface discontinuities interpreted as hidden fractures.

Ground Penetrating Radar (GPR) is a widespread technique to locate and characterise karst hazards (cavities and paleocollapses). In this paper, we show that the internal structure of sediments obtained from GPR surveys can also be used as an indicator of active karst processes. A classification of karst hazard problems by means of GPR in the GPR-doline triangle is proposed, with three end-members: cavities, evidences of subsidence and paleocollapses. These end members show particular signatures in the GPR-profiles. The field examples shown in this paper indicate that GPR survey is a geophysical technique that offers a very high resolution and provides structural and sedimentological information of the subsoil. The use of grid maps, elaborated from GPR data, is an efficient way to determine anomalous sectors (lateral changes of electromagnetic properties, different reflectivity and qualitative penetration depth variations or velocity wave propagation changes). Their relationships wit...

Cooper, A.H. 2020.  Geological hazards from salt mining, brine extraction and natural salt dissolution in the UK. in Giles, D. P. & Griffiths, J. S. (eds) 2020. Geological Hazards in the UK: Their Occurrence, Monitoring and Mitigation – Engineering Group Working Party Report. Geological Society, London, Engineering Geology Special Publications, 29, 369–387.

Salt mining along with natural and human-induced salt dissolution affects the ground over Permian and Triassic strata in the UK. In England, subsidence caused by salt mining, brine extraction and natural dissolution is known to have occurred in parts of Cheshire (including Northwich, Nantwich, Middlewich), Stafford, Blackpool, Preesall, Droitwich and Teeside/Middlesbrough; it
also occurs around Carrickfergus in Northern Ireland. Subsidence ranges from rapid and catastrophic failure to gentle sagging of the ground, both forms being
problematical for development, drainage and the installation of assets and infrastructure such as ground
source heat pumps. This paper reviews the areas affected by salt subsidence and details the mitigation measures that have been used; the implications for planning in such areas are also considered.