4D Geophysical Monitoring of Landslide Processes

This research project is a collaboration between British Geological Survey and University of Leeds and involves the development of hydrogeophysical imaging of rainfall-induced landslides which permit the observation of the temporal variation of the hydraulic processes taking place in the near-surface. Using Electrical Resistivity Tomography (ERT), characterisation of landslide structure is possible, as is the monitoring of seasonal accumulation and dissipation of soil moisture content. It is desirable to monitor and assess subsurface soil moisture content. The strength of soil – and hence its propensity to instability – changes as a result of soil moisture increase or decrease.

In addition to monitoring an active very slow-moving shallow landslide system located in North Yorkshire a number of laboratory experiments are being conducted with the aim of determining the resistivity-water saturation and pore suction-water saturation relationships for rock formations located at the field site. By relating subsurface volumetric moisture content and in-situ soil pore water pressure, landslide triggering processes will be better understood and potentially predictable. Undisturbed, cored soil samples from the field site are prepared in-house at the BGS and tested using purpose-built geophysical equipment at the University of Leeds.

Conventional landslide characterisation and geotechnical monitoring tools are also installed at the site and include RTK-DGPS (Differential GPS) of peg locations, piezometers positioned at the main failure surface, rain gauge and subsurface temperature sensors. The development of a ground model is an important part of the project, with soil strength parameters being determined at the Engineering Geology Laboratory, a facility of the MSc Engineering Geology. Through the analysis and interpretation of all available data sets an integrated approach to improve the understanding of landslide triggering processes is possible.

Field- and laboratory-based training courses on the MSc. Engineering Geology at the University of Leeds forms part of the training program for this project.