Strategy, location and sampling of the Lias Group (2) ground movements : shrink/swell project

The authors published a report in 2002 describing the sampling of argillaceous formations of the Lias Group at twenty-eight sites in South Wales, Eastern and Southern England. This report forms an addendum to the original report and describes the sampling of further Liassic formations in the counties of Nottinghamshire and Lincolnshire. Weathered and unweathered material was collected as undisturbed block samples and disturbed bulk samples from exposed faces. The samples were taken to give representative geotechnical properties of the lithostratigraphic formations of the Lias Group present at the sampling sites in a weathered and unweathered condition, if possible. The location of each site is described briefly and is indicated on a 1:50K OS map base. The stratigraphic units present at the site are listed and the site indicated on a 1:50K geological map base. Photographs of sections and sampling sites are also present. The types of samples taken from each site are specified and difficulties regarding the sampling are indicated where appropriate

Landslide and mass movement processes and their distribution in Longdendale Valley and Glossop District (sheet 86)

This report describes the geographical extent of the landslides and the mass movement mechanisms responsible for landslide deposits in the Longdendale valley. In addition an overview of the slope processes in the Glossop district is also presented

Landslide hazard assessment for National Rail Network

There have been a number of high profile reports of landslides on the national rail network of Great Britain (comprising England, Scotland and Wales) over recent years. Events range in size from small wash out failures (St. Bees, Cumbria) to well publicised large failures causing major longer term disruption (Hatfield Colliery, South Yorkshire). In conjunction with negative media attention, derailment and damage to railway infrastructure, failures along the rail network have the potential to cause injury and loss of life. The national rail network comprises ten strategic routes that cover a variety of terrains and geologies. The British Geological Survey (BGS) have produced, for Network Rail, a high level susceptibility model of landslide hazard from Outside Party Slopes adjacent to the strategic rail network. This assessment was compiled based on Geographic Information System (GIS) techniques and historical landslide records (landslide inventory). The model was designed to give a high level overview of potential landslide hazard to Network Rail senior management and individual Route Asset Managers. The national study adopted a fixed buffer style analysis of each 5 chain section (∼100 m length) of the entire railway network. It included event data from the BGS National Landslide Database superimposed on mapped data from the BGS GeoSure land instability susceptibility model and geologically mapped landslide polygons. The National Landslide Database is the most comprehensive inventory of landslide events in Great Britain. The BGS GeoSure slope instability layer provides a scientifically based 1:50 000 scale assessment of national susceptibility to natural slope failure. The results of this study have been provided as a spatially attributed dataset with total hazard susceptibility scores A (low)–E (high). Maximum hazard scores are attributed for both up and down- track and 5 chain length for the full network. A high score indicates where conditions imply a significant potential for future landslide hazard. Further refinement of the hazard layers are being developed by BGS to include specific landslide processes such as Rockfall, Earthflow and Debris Flow hazards

Slope dynamics project report : Holderness Coast - Aldbrough, survey & monitoring, 2001-2013

This report is a published product of an ongoing study by the British Geological Survey (BGS) of the coastal change at Aldbrough on the Holderness coast, East Riding of Yorkshire, UK. The test site at Aldbrough has been selected as one of the BGS Landslide Observatories because it is representative of the high rates of coastal recession along this stretch of the east coast. The Aldbrough Landslide Observatory is operated under the BGS ‘Slope Dynamics’ task within the BGS’s ‘Landslide’ project of the ‘Shallow Geohazards and Risk’ team. As well as providing new insights with respect to the volumetric rates of recession and the near surface processes, it is a focus for the trialling of new surface and subsurface monitoring technologies. The establishment of the Aldbrough observatory and the initial research findings are reported in a series of reports in addition to this report. These are: Hobbs, P.R.N., Jones, L.D., & Kirkham, M.P. (2015) Slope Dynamics project report: Holderness Coast – Aldbrough: Drilling & Instrumentation, 2012-2015. British Geological Survey, Internal Report No IR/15/001. Hobbs, P.R.N., Kirkham, M.P. & Morgan, D.J.R. (2016) Geotechnical laboratory testing of glacial deposits from Aldbrough, Phase 2 boreholes. British Geological Survey, Open Report No. OR/15/056. Whilst this report is focused on the survey and monitoring programme, it should be read in conjunction with the reports listed above, which provide further details on drilling and instrumentation and the geotechnical properties of the underlying geology. A series of reports will follow presenting the updated survey and monitoring reports, and their publication will be announced through the BGS project web page. Readers of these reports will probably also be interested in the context for this research, which can be found in: Hobbs, P.R.N., Pennington, C.V.L., Pearson, S.G., Jones, L.D., Foster, C., Lee, J.R., Gibson, A. (2008) Slope Dynamics Project Report: the Norfolk Coast (2000-2006). British Geological Survey, Open Report No. OR/08/018

Triaxial strength tests on till samples from the Slope Dynamics Project : Happisburgh, Sidestrand, and Aldborough

This report describes triaxial strength tests, and the results obtained, as carried out in the laboratories of the British Geological Survey on ‘undisturbed’ hand-prepared U100 samples of geological materials collected at test sites, forming part of the Slope Dynamics Project, at Happisburgh and Sidestrand (North Norfolk) and at Aldbrough (Holderness). The results are placed in the context of data available in the literature. Specimen preparation, test equipment, and test methodology are also briefly described

Characterisation, modelling and mapping of inland landslides using Laser Scanning and GPS

BGS capabilities in geomorphological mapping and slope monitoring have been significantly improved by the acquisition of a high-accuracy global positioning system (GPS) and terrestrially based LIght Distance And Ranging system (LIDAR). This equipment was originally purchased and developed by the BGS CliffScan project, (Project leader Peter Hobbs), part of the Coastal Geoscience and Global Change Programme. The aim of this project is to carry out sequential surveying and modelling of the changing profiles of various sites around the coast of England. Cliff sections provided a good basis for the scanning process, providing the user with good vertical and horizontal sections, constantly changing profiles and stable targets for back-sites (at most locations). The cliff sections also provided definitive breaks of slope i.e. the cliff junction with beach deposits and the top cliff line, which could also be recorded with the GPS. The development programme, undertaken as part of CliffScan has enabled BGS to gain experience in mapping and scanning coastal features. (Hobbs et al 2002, Gibson et al 2003 and Jones 2003). This experience has been applied and further developed by the Landslides Project for the application of these techniques to inland landsides

Landslide nature and distribution on the Market Rasen 1:50k geological sheet

This report describes the extent and character of the landslides and the mass movement processes in the area covered by the 1:50 000 scale BGS map of Market Rasen (Sheet 102). The work includes the identification of seven new landslide records to be added to the National Landslide Database. The work has assisted the continuing study of landslides and mass movements in Great Britain

Landslide and mass movement processes and their distribution in the Wellington district of Somerset

The British Geological Survey (BGS) has recently carried out a study of the slope processes that formed the landslide and mass movement deposits in the Wellington district of Somerset during the Quaternary. This landslide study, part of the continuing research into landslides and mass movement processes in Great Britain, recorded one hundred and eighteen landslides that were entered into the new National Landslide Database. The landslides were studied using walkover field survey and office-based remote sensing techniques. Significant past and current landslide activity was found to be associated with three distinct slope behaviour units, which are defined by their bedrock geology and topology. The Upper Greensand Formation overlying the Mercia Mudstone Group defined slope behaviour unit A, the Upper Greensand Formation overlying the Lias Group identified slope behaviour unit B and the Penarth Group overlying the Mercia Mudstone Group, slope behaviour unit C. Geomorphological models for these units were created which described the landslide processes and the deposits that they engendered. The research in this area also enabled further refinement of the ‘landslide domain’ concept, which is being developed as a better way of describing and depicting the distribution of the wide range of landslides and mass movement deposits that are the result of the complex interaction of geological materials and climatic changes during the Quaternary

Controls on the magnitude-frequency scaling of an inventory of secular landslides

Linking landslide size and frequency is important at both human and geological timescales for quantifying both landslide hazards and the effectiveness of landslides in the removal of sediment from evolving landscapes. The statistical behaviour of the magnitude-frequency of landslide inventories is usually compiled following a particular triggering event such as an earthquake or storm, and their statistical behaviour is often characterised by a power-law relationship with a small landslide rollover. The occurrence of landslides is expected to be influenced by the material properties of rock and/or regolith in which failure occurs. Here we explore the statistical behaviour and the controls of a secular landslide inventory (SLI) (i.e. events occurring over an indefinite geological time period) consisting of mapped landslide deposits and their underlying lithology (bedrock or superficial) across the United Kingdom. The magnitude-frequency distribution of this secular inventory exhibits an inflected power-law relationship, well approximated by either an inverse gamma or double Pareto model. The scaling exponent for the power-law scaling of medium to large landslides is � = −1.71 ± 0.02. The small-event rollover occurs at a significantly higher magnitude (1.0–7.0 × 10−3 km2) than observed in single-event landslide records (� 4 × 10−3 km2).We interpret this as evidence of landscape annealing, from which we infer that the SLI underestimates the frequency of small landslides. This is supported by a subset of data where a complete landslide inventory was recently mapped. Large landslides also appear to be under-represented relative to model predictions. There are several possible reasons for this, including an incomplete data set, an incomplete landscape (i.e. relatively steep slopes are under-represented), and/or temporal transience in landslide activity during emergence from the last glacial maximum toward a generally more stable late-Holocene state. The proposed process of landscape annealing and the possibility of a transient hillslope response have the consequence that it is not possible to use the statistical properties of the current SLI database to rigorously constrain probabilities of future landslides in the UK