Abstract
Moisture-induced landslides are a global geohazard; mitigating the risk posed by landslides requires an understanding of the hydrological and geological conditions present within a given slope. Recently, numerous geophysical studies have been attempted to characterise slow-moving landslides, with an emphasis on developing geoelectrical methods as a hydrological monitoring tool. However, landslides pose specific challenges for processing geoelectrical data in long-term monitoring contexts as the sensor arrays can move with slope movements. Here we present an approach for processing long-term (over 8 years) geoelectrical monitoring data from an active slow-moving landslide, Hollin Hill, situated in Lias rocks in the southern Howardian Hills, UK. These slope movements distorted the initial setup of the monitoring array and need to be incorporated into a time-lapse resistivity processing workflow to avoid imaging artefacts. We retrospectively sourced seven digital terrain models to inform the topography of our imaging volumes, which were acquired by either Unmanned Aerial Vehicle (UAV)-based photogrammetry or terrestrial laser ranging systems. An irregular grid of wooden pegs was periodically surveyed with a global position system, from which distortions to the terrain model and electrode positions can be modelled with thin plate splines. In order to effectively model the time-series electrical resistivity images, a baseline constraint is applied within the inversion scheme; the result of the study is a time-lapse series of resistivity volumes which also incorporate slope movements. The workflow presented here should be adaptable for other studies focussed on geophysical/geotechnical monitoring of unstable slopes.
Highlights
Landslides are a global phenomenon, resulting in severe economic and societal losses, and as such represent a significant geohazard
Landslide kinematics The modelling of the electrode movements allows for an assessment of landslide kinematics at Hollin Hill (e.g., Hutchinson 1983) over a 10-year period, Fig. 6 illustrates the direction and relative magnitude of lateral electrode movements
At the end of 2012, downslope movements have been observed on the eastern flow lobe, which are accompanied up slope with a rotational failure just to the east of the monitoring array, affecting the electrodes on line 5
Summary
Landslides are a global phenomenon, resulting in severe economic and societal losses, and as such represent a significant geohazard. In order to manage this hazard, it is necessary to characterise landslide bodies both internally and externally. The external geomorphology of unstable slopes can be characterised directly with observations, aerial imagery and laser ranging methods. Determining the internal structure of landslides remains more challenging, often practitioners need to rely on point sensors and physical samples (recovered from pits or core). Bogoslovsky and Ogilvy (1977) first demonstrated that geoelectrical techniques could be used to make interpretations on the structure of landslides and likely hydrological conditions, as relationships between electrical resistivity and moisture content have been long established (e.g., Archie 1947) Over the past few decades, several studies and reviews have investigated the use of geophysical methods for landslide investigation since they are spatially sensitive, non-invasive and comparatively inexpensive relative to conventional shallow borehole investigations (Jongmans and Garambois 2007; Pazzi et al 2019; Whiteley et al 2019). Bogoslovsky and Ogilvy (1977) first demonstrated that geoelectrical techniques could be used to make interpretations on the structure of landslides and likely hydrological conditions, as relationships between electrical resistivity and moisture content have been long established (e.g., Archie 1947)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
