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Natural hazards

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    The GeoSure data sets and reports from the British Geological Survey provide information about potential ground movement or subsidence in a helpful and user-friendly format. The reports can help inform planning decisions and indicate causes of subsidence. The methodology is based on BGS DiGMap (Digital Map) and expert knowledge of the behaviour of the formations so defined. This dataset provides an assessment of the potential for dissolution within a geological deposit. Ground dissolution occurs when certain types of rock contain layers of material that may dissolve if they get wet. This can cause underground cavities to develop. These cavities reduce support to the ground above and can lead to a collapse of overlying rocks. Dissolution of soluble rocks produces landforms and features collectively known as 'karst'. Britain has four main types of soluble or 'karstic' rocks; limestone, chalk, gypsum and salt, each with a different character and associated potential hazards. Engineering problems associated with these karstic rocks include subsidence, sinkhole formation, uneven rock-head and reduced rock-mass strength. Sinkhole formation and subsidence has the potential to cause damage to buildings and infrastructure. Complete Great Britain national coverage is available. The storage formats of the data are ESRI and MapInfo but other formats can be supplied.

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    The GeoSure data sets and reports from the British Geological Survey provide information about potential ground movement or subsidence in a helpful and user-friendly format. The reports can help inform planning decisions and indicate causes of subsidence. The methodology is based on BGS DiGMap (Digital Map) and expert knowledge of the behaviour of the formations so defined. This dataset provides an assessment of the potential for a geological deposit to compress under an applied load, a characteristic usually of superficial deposits such as peat or alluvium. Some types of ground may contain layers of very soft materials like clay or peat. These may compress if loaded by overlying structures, or if the groundwater level changes, potentially resulting in depression of the ground and disturbance of foundations. Complete Great Britain national coverage is available. The storage formats of the data are ESRI and MapInfo but other formats can be supplied.

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    The GeoSure data sets and reports from the British Geological Survey provide information about potential ground movement or subsidence in a helpful and user-friendly format. The reports can help inform planning decisions and indicate causes of subsidence. The methodology is based on BGS DiGMap (Digital Map) and expert knowledge of the behaviour of the formations so defined. This dataset provides an assessment of the potential for a geological deposit to show running sand behaviour under the action of flowing water, a characteristic usually of saturated sand and silt grade material. Complete Great Britain national coverage is available. The storage formats of the data are ESRI and MapInfo but other formats can be supplied.

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    The GeoSure data sets and reports from the British Geological Survey provide information about potential ground movement or subsidence in a helpful and user-friendly format. The reports can help inform planning decisions and indicate causes of subsidence. The methodology is based on BGS DiGMap (Digital Map) and expert knowledge of the behaviour of the formations so defined. This dataset provides an assessment of the potential for a geological deposit to shrink and swell. Many soils contain clay minerals that absorb water when wet (making them swell), and lose water as they dry (making them shrink). This shrink-swell behaviour is controlled by the type and amount of clay in the soil, and by seasonal changes in the soil moisture content (related to rainfall and local drainage). The rock formations most susceptible to shrink-swell behaviour are found mainly in the south-east of Britain. Clay rocks elsewhere in the country are older and have been hardened by burial deep in the earth and are less able to absorb water. The BGS has carried out detailed geotechnical and mineralogical investigations into rock types known to shrink, and are modelling their properties across the near surface. This research underpins guidance contained in the national GeoSure dataset, and is the basis for our responses to local authorities, companies and members of the public who require specific information on the hazard in their areas. The BGS is undertaking a wide-ranging research programme to investigate this phenomenon by identifying those areas most at risk and developing sustainable management solutions. Complete Great Britain national coverage is available. The storage formats of the data are ESRI and MapInfo but other formats can be supplied.

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    The joint PHE-GSNI-BGS digital Indicative Atlas of Radon in Northern Ireland presents an overview of the results of detailed mapping of radon potential, defined as the estimated percentage of homes in an area above the radon Action Level. The Indicative Atlas of Radon in Northern Ireland presents a simplified version of the Radon Potential Dataset for Northern Ireland, with each 1-km grid square being classed according to the highest radon potential found within it, so is indicative rather than definitive. The Radon Potential Dataset for Northern Ireland provides the current definitive map of radon Affected Areas in Northern Ireland. The Indicative Atlas of Radon in Northern Ireland is published in Z Daraktchieva, J D Appleton, D M Rees, K A M Adlam, A H Myers, S A Hodgson, N P McColl, G R Wasson and L J Peake, 2015. Indicative Atlas of Radon in Northern Ireland. PHE-CRCE-017, 22 pp. Radon is a natural radioactive gas, which enters buildings from the ground. Exposure to high concentrations increases the risk of lung cancer. Public Health England (PHE) recommends that radon levels should be reduced in homes where the annual average exceed 200 becquerels per cubic metre (200 Bq m-3), the radon Action Level. Public Health England defines radon Affected Areas as those with 1% chance or more of a house having a radon concentration exceeding the Action Level.

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    GeoSure Basic is a single, combined GeoSure model, based on the 6 geohazard layers produced for the GeoSure dataset package. The methodology behind GeoSure Basic uses only the highest score of all the GeoSure layers, which cover: Collapsible Deposits, Compessible Ground, Landslides, Running Sand, Shrink Swell, and Dissolution. The resulting model has been re-classified to show 'Negligible - Very Low', 'Low', and 'Moderate - High' potential for natural geohazards. Complete Great Britain national coverage is available.

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    The newGeoSure Insurance Product (newGIP) provides the potential insurance risk due to natural ground movement. It incorporates the combined effects of the 6 GeoSure hazards on (low-rise) buildings. This data is available as vector data, 25m gridded data or alternatively linked to a postcode database – the Derived Postcode Database. A series of GIS (Geographical Information System) maps show the most significant hazard areas. The ground movement, or subsidence, hazards included are landslides, shrink-swell clays, soluble rocks, running sands, compressible ground and collapsible deposits. The newGeoSure Insurance Product uses the individual GeoSure data layers and evaluates them using a series of processes including statistical analyses and expert elicitation techniques to create a derived product that can be used for insurance purposes such as identifying and estimating risk and susceptibility. The Derived Postcode Database (DPD) contains generalised information at a postcode level. The DPD is designed to provide a ‘summary’ value representing the combined effects of the GeoSure dataset across a postcode sector area. It is available as a GIS point dataset or a text (.txt) file format. The DPD contains a normalised hazard rating for each of the 6 GeoSure themes hazards (i.e. each GeoSure theme has been balanced against each other) and a combined unified hazard rating for each postcode in Great Britain. The combined hazard rating for each postcode is available as a standalone product. The Derived Postcode Database is available in a point data format or text file format. It is available in a range of GIS formats including ArcGIS (*.shp), ArcInfo Coverages and MapInfo (*.tab). More specialised formats may be available but may incur additional processing costs. The newGeoSure Insurance Product dataset has been created as vector data but is also available as a raster grid. This data is available in a range of GIS formats, including ArcGIS (*.shp), ArcInfo coverage’s and MapInfo (*.tab). More specialised formats may be available but may incur additional processing costs. Data for the newGIP is provided for national coverage across Great Britain. The newGeoSure Insurance Product dataset is produced for use at 1:50 000 scale providing 50 m ground resolution. This dataset has been specifically developed for the insurance of low-rise buildings. The GeoSure datasets have been developed to identify the potential hazard for low-rise buildings and those with shallow foundations of less than 2 m deep. The identification of ground instability and other geological hazards can assist regional planners; rapidly identifying areas with potential problems and aid local government offices in making development plans by helping to define land suited to different uses. Other users of these data may include developers, homeowners, solicitors, loss adjusters, the insurance industry, architects and surveyors. Version 7 released June 2015.

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    The GeoSure data sets and reports from the British Geological Survey provide information about potential ground movement or subsidence in a helpful and user-friendly format. The reports can help inform planning decisions and indicate causes of subsidence. Complete Great Britain national coverage is available. GeoSure Basic is a single, combined GeoSure model, containing only the highest score of all the GeoSure layers. The model has been re-classified to negligible - very low, low and moderate - high. The methodology is based on the 6 GeoSure individual hazard Assessments. The storage formats of the data are ESRI and MapInfo but other formats can be supplied.

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    The GeoSure data sets and reports from the British Geological Survey provide information about potential ground movement or subsidence in a helpful and user-friendly format. The reports can help inform planning decisions and indicate causes of subsidence. The methodology is based on BGS DiGMap (Digital Map) and expert knowledge of the behaviour of the formations so defined. This dataset provides an assessment of slope instability. Landslide hazard occurs due to particular slope characteristics (such as geology, gradient, sources of water, drainage, man-made constructions) combining to cause the slope to become unstable. Downslope movement of materials, such as a landslide or rockfall may lead to a loss of support and damage to buildings. Complete Great Britain national coverage is available. The storage formats of the data are ESRI and MapInfo but other formats can be supplied.

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    The GeoSure datasets and related reports from the British Geological Survey provide information about potential ground movement due to six types of natural geological hazard, in a helpful and user-friendly format. The reports can help inform planning decisions and indicate causes of subsidence. The Collapsible Ground dataset provides an assessment of the potential for a geological deposit to collapse (to subside rapidly) as a consequence of a metastable microfabric in loessic material. Such metastable material is prone to collapse when it is loaded (as by construction of a building, for example) and then saturated by water (as by rising groundwater, for example). Collapse may cause damage to overlying property. The methodology is based on BGS DiGMapGB-50 (Digital Map) and expert knowledge of the origin and behaviour of the formations so defined. It provides complete coverage of Great Britain, subject to revision in line with changes in DiGMapGB lithology codes and methodological improvements. The storage formats of the data are ESRI and MapInfo but other formats can be supplied.