This page explains the data available for the National Landslide Database (NLD) and accessed under the BGS GeoIndex under the following headings:
- What do the symbols mean?
- How is the point location accuracy expressed?
- How do I get a map of the landslide extent?
- Where have the data come from?
- Where can I obtain the references given in the table?
- What are the caveats to the data and its collection?
- Terms and conditions — important information about how to use NLD data
The National Landslide Database holds over 17 500 records of landslides and is the definitive source of landslide information for Great Britain; it excludes Northern Ireland, Isle of Man and the Channel Islands.
What do the symbols mean?
Each landslide within the National Landslide Database is identified by a National Landslide Database ID number and a point location, as shown on this map. The National Landslide ID and Survey number represents an individual survey of a landslide, rather than the landslide itself. This is because there could be several phases of movement within or extensions to the same landslide, particularly if it is a large and complex one. Subsequent surveys of the same landslide may be recorded in the database with the same National Landslide Database ID number but with a new Survey Number.
|Land slide ID||10741|
|Location||South of Scarborough, North Yorkshire, England|
|Grid checked by BGS||Y|
|Date of landslide||03 June 1993|
|Date known to the nearest||Day|
|Reference||Holbeck Hall case study|
The point symbols at the designated location do not reflect the size and shape of the corresponding landslide, but the recorded reference of a landslide within a range of accuracy.
Where possible, each entry is located at the highest point on the landslide backscarp feature. This is not always possible to locate as, for example, backscarp information is commonly omitted from older geological maps. In these cases, the highest point on the mapped landslide polygon is used. If this information is not available, the entry is located approximately.
In the 1990s, BGS inherited approximately 8500 landslide records from the then Department of Environment (DoE). This survey was carried out by Geomorphological Services Limited (GSL) and involved their staff searching through the literature, including BGS maps and reports, to gain as much information about landslides in Great Britain as possible.These landslides were recorded as either six-figure grid references (1 km accuracy) or eight-figure grid references (100 m accuracy) thereby incorporating a large locational inaccuracy when displayed on a map. The BGS Landslides Team has been working for several years to re-locate these landslides with more accuracy and to remove duplicates or incorrect entries inherited from the DoE database. This process is still underway and will take several more years to complete.
Consequently, the data are displayed in the GeoIndex to show whether the source of the landslide record has been validated by the team.
|Y||The Landslides Team have validated this landslide point correctly to within a range of accuracy.|
|N||The Landslides Team is yet to validate this landslide.|
|+||U||The Landslides Team has tried to find information about this landslide but the original reference material is unavailable.|
What are the caveats to the data and its collection?
Whilst the National Landslide Database is the most compressive list of GB landslides it is not a complete factual record of every landslide that has occurred in the last 100 years; rather it is a record of landslides that have been identified through a range of sources.
Landslide dates – BGS does not always know when a landslide occurred, where this is known it is recorded however dated landslides are limited.
BGS have not always recorded events that happened on engineered slopes (e.g. cuttings or embankments) as these are not deemed natural slope failures. These are a relatively new addition and identified as ‘Slope Failures’ they are now included in the National Landslide Database as these were the most prominent ‘landslides’ during the increased frequency of events recorded in 2012.
Improved media search engines and the incorporation of slope failures (i.e. these engineered slopes), as well as the use of social media for data gathering has improved our access to data and this is visible in the data. Consequently, care must be taken in the interpretation. The number of ‘recent’ landslides detected by media search engines and social media before August 2012 is far fewer. This reflects a previously reduced capability in data gathering as opposed to fewer landslides occurring and is an inevitable obstacle to collecting data over long periods of time in the context of technological advancements. The widespread use of smartphones has dramatically increased the incidence, detail and speed of data reporting.
BGS inherited the database in the 1990’s, before this no organisation was systematically collecting landslide events. The pre 2000 part of the visualisation may not represent a lower number of landslides just a lack of recording of them.
A key factor for consideration is that BGS is more likely to hear about an event if it has had an impact.
These caveats are further discussed in Pennington et al. 2014.
Terms and conditions — important information about how to use NLD data
Additional important factors apply to the National Landslide Database data:
- Landslides, by definition, are a mass of soil, rock or debris that has moved, or is still in the process of moving, down slope. It is therefore possible that the mass may have moved since the survey was carried out and the data was recorded in the National Landslide Database. This applies to both paper and digitally mapped landslides.
- The data, information and related records supplied by BGS can only be indicative and should not be taken as a substitute for specialist interpretations, professional advice and/or detailed ground investigations. The data must not be used for insurance purposes. You must seek professional advice before making technical interpretations on the basis of the materials provided.
- Landslides are named according to the source of information. If the landslide was named by the aforementioned DoE database, published work (e.g. journal publication, report), newspaper or other media, then that name has been retained. If the landslide has been taken from British Geological Survey geology maps, the landslide is named according to the nearest available landmark. In some areas, particularly remote locations, this can be, for example, the name of a woodland, hill, road, settlement, cliff, farm or any other building on the Ordnance Survey map. The landslide names are nominal only and in no way reflect the size, activity or nature of the landslide.
- Geological observations and interpretations of landslides are made according to the prevailing understanding of the subject at the time of the survey. The quality of such observations and interpretations may be affected by the availability of new data, by subsequent advances in knowledge, improved methods of interpretation, and better access to sampling locations.
- Raw data may have been transcribed from analogue to digital format, or may have been acquired by means of automated measuring techniques. Although such processes are subjected to quality control to ensure reliability where possible, some raw data may have been processed without human intervention and may in consequence contain undetected errors.
- Data may be compiled from the disparate sources of information available to BGS, including material donated to BGS by third parties, and that may not originally have been subject to any verification or other quality control process.
- Data, information and related records, which have been donated to BGS, have been produced for a specific purpose, and that may affect the type and completeness of the data recorded and any interpretation. The nature and purpose of data collection, and the age of the resultant material may render it unsuitable for certain applications/uses. You must verify the suitability of the material for your intended usage.
Copyright in materials derived from the British Geological Survey’s work, is owned by the United Kingdom Research and Innovation (UKRI) and/or the authority that commissioned the work. You may not copy or adapt the data, or provide it to a third party, without first obtaining UKRI’s permission. Please visit the IPR web pages or contact the BGS Head of Intellectual Property Rights, British Geological Survey, Environmental Science Centre, Keyworth, Nottingham NG12 5GG. Telephone: 0115 936 3100. Email: email@example.com.
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Contact the Landslide Team
British Geological Survey
Email: Landslides team
Telephone: 0115 936 3143