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Natural hazards

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  • This addition to the GeoSure ground stability data consists of a single data layer in Geographical Information System (GIS) format that identifies areas of potential shrink-swell hazard at subcrop level (up to 10 metres depth) in Great Britain. It is essentially a national hazard susceptibility map. This data has been produced by geologists, geotechnical specialists and information developers at the British Geological Survey and is presented as a GIS data layer. Swelling clays can change volume due to variation in moisture, this can cause ground movement, particularly in the upper two metres of the ground that may affect many foundations. Ground moisture variations may be related to a number of factors, including weather variations, vegetation effects (particularly growth or removal of trees) and the activities of people. Such changes can affect building foundations, pipes or services.

  • The 5km Hex GS Shrink Swell dataset shows a generalised view of the GeoSure Shrink Swell v8 dataset to a hexagonal grid resolution of 64.95km coverage area (side length of 5km). This dataset indicates areas of potential ground movement in a helpful and user-friendly format. The rating is based on a highest level of susceptibility identified within that Hex area: Low (1), Moderate (2), Significant (3). Areas of localised significant rating are also indicated. The summarising process via spatial statistics at this scale may lead to under or over estimation of the extent of a hazard. The supporting GeoSure reports can help inform planning decisions and indicate causes of subsidence. The Shrink Swell methodology is based on the BGS Digital Map (DiGMapGB-50) 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 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.

  • 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.

  • The joint PHE-GSNI-BGS digital Radon Potential Dataset for Northern Ireland provides the current definitive map of radon Affected Areas in Northern Ireland. The Radon Potential map for Northern Ireland shows the estimated percentage of homes in an area exceeding the radon Action Level. This is the basic information to assigning the level of protection required for new buildings and extensions, as described in the Building Research Establishment guidance BR-413 Radon: Guidance on protective measures for new dwellings in Northern Ireland (2004). The Radon Potential map for Northern Ireland is based on PHE indoor radon measurements and 1:10 000 or 1: 250 000 scale digital geology information provided by the Geological Survey of Northern Ireland (GSNI). The indoor radon data is used with the agreement of the Northern Ireland Environment Agency and PHE. Confidentiality of measurement locations is maintained through data management practices. Access to the data is restricted. 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 Action Level. PHE defines radon Affected Areas as those with 1% chance or more of a house having a radon concentration at or above the Action Level. Further information on radon can be obtained from www.ukradon.org

  • 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.

  • The 5km Hex GS Running Sand dataset shows a generalised view of the GeoSure Running Sand v7 dataset to a hexagonal grid resolution of 64.95km coverage area (side length of 5km). This dataset indicates areas of potential ground movement in a helpful and user-friendly format. The rating is based on a highest level of susceptibility identified within that Hex area: Low (1), Moderate (2), Significant (3). Areas of localised significant rating are also indicated. The summarising process via spatial statistics at this scale may lead to under or over estimation of the extent of a hazard. The supporting GeoSure reports can help inform planning decisions and indicate causes of subsidence. The Running Sand methodology is based on the BGS Digital Map (DiGMapGB-50) 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 data shows the extent of mining within Great Britain it was captured in 1990 by OVE ARUP on behalf of the Department of Environment as a series of paper maps and no updates have been carried out. The data has been converted to a digital format (ESRI shape file) by BGS in 1995. The original scale of the data was 1km square. The dataset has limited attribution indicating type i.e. metalliferous, rock, coal, deneholes (chalk), evaporites or ironstone, and whether definitive evidence was found. Although every effort has been made to attribute the digital data to the original maps some inconstancies may have arisen due to data conversion process.

  • The BGS Debris Flow Susceptibility Model for Great Britain v6.1 is a 1:50 000 scale raster dataset of Great Britain providing 50 m ground resolution information on the potential of the ground, at a given location, to form a debris flow. It is based on a combination of geological, hydrogeological and geomorphological data inputs and is primarily concerned with potential ground stability related to natural (rather than man-made) geological conditions and slopes. The dataset is designed for those interested specifically in debris flow susceptibility at a regional or national planning scale such as those involved in construction or maintenance of infrastructure networks (road or rail or utilities), or other asset managers such as for property (including developers and home owners), loss adjusters, surveyors or local government. The dataset builds on research BGS has conducted over the past 15 years investigating debris flows. The model was designed to identify potential source-areas for debris flows rather than locate where material may be deposited following a long-run-out failure i.e. the track and flow of debris. This work focuses on natural geological and geomorphological controls that are likely to influence the initiation of debris flows. It therefore, does not consider the influence of land use or land cover factors.

  • The 5km Hex GS Running Sand dataset shows a generalised view of the GeoSure Running Sand v8 dataset to a hexagonal grid resolution of 64.95km coverage area (side length of 5km). This dataset indicates areas of potential ground movement in a helpful and user-friendly format. The rating is based on a highest level of susceptibility identified within that Hex area: Low (1), Moderate (2), Significant (3). Areas of localised significant rating are also indicated. The summarising process via spatial statistics at this scale may lead to under or over estimation of the extent of a hazard. The supporting GeoSure reports can help inform planning decisions and indicate causes of subsidence. The Running Sand methodology is based on the BGS Digital Map (DiGMapGB-50) 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.