Search

The paper outlines landslide mapping and change-detection monitoring protocols based on the successes of ICL-IPL Project 202 in southwestern British Columbia, Canada. In this region, ice sheets, glaciers, permafrost, rivers and oceans, high relief, and biogeoclimatic characteristics contribute to produce distinctive landslide assemblages. Bedrock and drift-covered slopes along the transportation corridors are prone to mass-wasting when favourable conditions exist. In high-relief mountainous areas, rapidly moving landslides include rock and debris avalanches, rock and debris falls, debris flows and torrents, and lahars. In areas with moderate to low relief, rapid to slow mass movements include rockslides and slumps, debris or earth slides and slumps, and earth flows. Slow-moving landslides include rock glaciers, rock and soil creep, solifluction, and lateral spreads in bedrock and surficial deposits. Research in the Thompson River Valley aims to gain a better understanding of how geological conditions, extreme weather events and climate change influence landslide activity along the national railway corridor. Remote sensing datasets, consolidated in a geographic information system, capture the spatial relationships between landslide distribution and specific terrain features, at-risk infrastructure, and the environmental conditions expected to correlate with landslide incidence and magnitude. Reliable real-time monitoring solutions for critical railway infrastructure (e.g., ballast, tracks, retaining walls, tunnels and bridges) able to withstand the harsh environmental conditions of Canada are highlighted. The provision of fundamental geoscience and baseline geospatial monitoring allows stakeholders to develop robust risk tolerance, remediation, and mitigation strategies to maintain the resilience and accessibility of critical transportation infrastructure, while also protecting the natural environment, community stakeholders, and the Canadian economy. We conclude by proposing a best-practice solution involving three levels of investigation to describe the form and function of the wide range of rapid and slow-moving landslides occurring across Canada, which is also applicable elsewhere.

This International Programme on Landslide (IPL) Project 202 paper presents a scalable remote piloted aircraft system (RPAS) platform that streamlines unoccupied aerial vehicle (UAV) flight operations for data capture, cloud processing and image rendering to inventory and monitor slow-moving landslides along the national railway transportation corridor in southwestern British Columbia, Canada. Merging UAV photogrammetry, ground-based real-time kinematic global navigation satellite system (RTK-GNSS) measurements, and satellite synthetic aperture radar interferometry (InSAR) datasets best characterizes the distribution, morphology and activity of landslides over time. Our study shows that epochal UAV photogrammetry, benchmarked with periodic ground-based RTK-GNSS measurements and satellite InSAR platforms with repeat visit times of weeks (e.g., RADARSAT-2 and SENTINEL-1) to days (e.g. RADARSAT Constellation Mission) provides rapid landslide monitoring capability with cm-scale precision and accuracy.

Developments in time-lapse electrical resistivity tomography (ERT) technology are transforming our ability to monitor the subsurface due to purpose-built monitoring instruments, advances in automation and modeling, and the resulting improvements in spatial and temporal resolution. We describe the development of a novel ERT-based remote monitoring system called PRIME that integrates new low-power measurement instrumentation with data delivery, automated data processing and image generation, and web-based information delivery. Due to the sensitivity of ERT to hydrologic processes in the near surface, we focus on the application of PRIME for moisture-driven landslide monitoring. Case examples are considered of landslides in engineered and natural slopes, including those impacting geotechnical assets in rail and highways, where slope hydrology is seen to be controlled by lithology, vegetation, fissuring, and drainage structures. We conclude by taking a forward look at emerging developments in ERT monitoring relating to hardware, software and modeling, and applications.

In this research note, we demonstrate the applicability of interferometric analyses (InSAR) of RADARSAT 2 (RS2), SENTINEL 1 (S1) and RADARSAT Constellation Mission (RCM) datasets to characterize an...

A study of factors impacting landslide displacement rates was conducted on the Ripley Landslide within the Thompson River valley in British Columbia, Canada for the International Programme on Landslides’ project #202. Seasonal and multiyear changes in atmospheric factors cause cyclic fluctuation of matric suction in the vadose zone through changes to the in situ water content. The ingress of moisture is shown to contribute to multiyear and seasonal loss of stability causing increasing landslide displacement rates, often disregarded in slope stability calculations. However, the water content in the unsaturated zone is important, especially in semi-arid to arid climates where the water table is low and large portions of the slope are unsaturated. Additional tools for studying long-term variations in climate and seasonal changes in water content are presented. These tools are used to characterize historical climate and compare several factors that have resulted in changing landslide displacement rates and magnitude. Infiltration of precipitation and snowmelt directly contributes to matric suction loss in the head scarp and is exacerbated by the presence of tension cracks. While groundwater levels are often correlated to changing displacement rates, changes in matric suction can also influence the rates of displacement. Climatic trends over subsequent years alter the long-term soil water accumulation which impacts rates of landslide displacement. By accounting for additional strength, or potentially a loss in strength due to increasing water content, it is possible to develop a more complete understanding of the mechanisms of climate change which drive displacement rates in the translational, metastable earthen slides that dominate the Thompson River valley. These mechanisms can be applied to comparable river valleys around the world.

The combination of an increasingly assertive Russia with growing uncertainty over long-term US commitment to Europe's security has resulted in calls for new efforts to be made in European defence c...

Landslides along a 10 km reach of Thompson River south of Ashcroft, British Columbia, have repeatedly damaged vital railway infrastructure, while also placing public safety, the environment, natural resources, and cultural heritage features at risk. Government agencies, universities, and the railway industry are focusing research efforts on a representative test site — the very-slow-moving Ripley Landslide — to manage better the geohazard risk in this corridor. We characterize the landslide’s form and function through hydrogeological and geophysical mapping. Field mapping and exploratory drilling distinguish 10 hydrogeological units in surficial deposits and fractured bedrock. Electrical resistivity tomography, frequency domain electromagnetic conductivity measurements, ground-penetrating radar, seismic pressure wave refraction, and multispectral analysis of shear waves; in conjunction with downhole measurement of natural gamma radiation, induction conductivity, and magnetic susceptibility provide a detailed, static picture of soil moisture and groundwater conditions within the hydrogeological units. Differences in electrical resistivity of the units reflect a combination of hydrogeological characteristics and climatic factors, namely temperature and precipitation. Resistive earth materials include dry glaciofluvial outwash and nonfractured bedrock; whereas glaciolacustrine clay and silt, water-bearing fractured bedrock, and periodically saturated subglacial till and outwash are conductive. Dynamic, continuous real-time monitoring of electrical resistivity, now underway, will help characterize water-flow paths, and possible relationships to independently monitor pore pressures and slope creep. These new hydrogeological and geophysical data sets enhance understanding of the composition and internal structure of this landslide and provide important context to interpret multiyear slope stability monitoring ongoing in the valley. University College Dublin

Landslides in the Thompson River Valley, British Columbia, Canada, threaten the serviceability of two railway lines that connect Vancouver to the rest of Canada and the US. To minimise the impact of slope instability on vital transport infrastructure, as well as on terrestrial and aquatic ecosystems, public safety, communities, local heritage, and the economy, and to better inform decision making, there is a need for monitoring. Since 2013, the Ripley Landslide – a small, slow-moving, translational landslide – has been the focus of monitoring efforts in the Thompson River Valley transportation corridor. In November 2017, a novel Electrical Resistivity Tomography (ERT) monitoring system was installed on the site, providing near-real-time data collection via a telemetric link. 4-Dimensional resistivity models are presented in the context of moisture content and soil suction, two parameters known to influence slope stability in the Thompson River Valley. Here, we discuss the development of laboratory-based petrophysical relationships that relate electrical resistivity to moisture content and soil suction directly, building on relationships developed in the field. The 4-D ERT models were calibrated using these petrophysical relationships to provide insights into the complex spatial and temporal variations in moisture content and soil suction. This study highlights the utility of geoelectrical monitoring for assessing slope stability in the context of moisture-driven landslides.

Instability of slopes, embankments, and cuttings on the railway network is increasingly prevalent globally. Monitoring vulnerable infrastructure aids in geotechnical asset management, and improvements to transport safety and efficiency. Here, we examine the use of a novel, near-real-time Electrical Resistivity Tomography (ERT) monitoring system for assessing the stability of a railway cutting in Leicestershire, United Kingdom. In 2015, an ERT monitoring system was installed across a relict landslide (grassed) and an area of more stable ground on either side (wooded), to monitor changes in electrical resistivity through time and space, and to assess the influence of different types of vegetation on the stability of transportation infrastructure. Two years of 4-Dimensional ERT monitoring results are presented here, and petrophysical relationships developed in the laboratory are applied to calibrate the resistivity models in order to provide an insight into hydrogeological pathways within a railway cutting. The influence of vegetation type on subsurface moisture pathways and on slope stability is also assessed – here we find that seasonal subsurface changes in moisture content and soil suction are exacerbated by the presence of trees (wooded area). This results in shrink-swell behaviour of the clays comprising the railway cutting, resulting in fissuring and a reduction in shear strength, leading to instability. As such, it is proposed that on slopes comprised of expansive soils, grassed slopes are beneficial for stability. Insights into the use of 4-D ERT for monitoring railway infrastructure gained from this study may be applied to the monitoring of critical geotechnical assets elsewhere.

Differential interferometric analysis of RADARSAT Constellation Mission (RCM) synthetic aperture radar (DInSAR) datasets provides insight into the spatial and temporal distribution of landslides impacting a critical section of the national railway transportation corridor in mountainous western Canada. This study demonstrates that monitoring unstable slopes and infrastructure with RCM is a cost-effective hazard management and risk reduction tool.

Landslides in the Thompson River valley, British Columbia have the potential to adversely impact vital national railway infrastructure and operations, the natural environment, cultural heritage features, communities, public safety and the economy. To better manage geohazard risks in the primary national transportation corridor, government agencies, universities and railway industry partners are focusing research efforts on the Ripley Landslide, 7 km south of Ashcroft. The internal composition and structure of this very slow-moving landslide as revealed by geophysical surveys and terrain mapping provides contextual baseline data for interpreting slope stability monitoring results and guiding geohazard mitigation efforts. Terrestrial and waterborne geophysical surveys were undertaken using subsets of the following methods: electrical resistivity tomography, frequency electromagnetic conductivity, ground penetrating radar, primary-wave refraction and multispectral analysis of shear-waves, natural gamma radiation, induction conductivity and magnetic susceptibility. Small and irregular anomalies, areas of complex subsurface geometry and groundwater-rich zones are resolved along all terrestrial geophysical survey lines. Terrain mapping and geophysical surveys indicate a high relief bedrock sub-surface overlain by a 10 m to >30 m thick package of complex fine-grained sediments containing groundwater. Planar sub-surface features revealed in surface exposures, borehole logs and geophysical profiles include tabular bedding and terrain unit contacts. Profiles also show discrete curvilinear features interpreted as rotational-translational failure planes in clay-rich beds in the main body of the slide beneath the rail ballast and retaining wall. Integrating data from surficial geology mapping and an array of geophysical methods provided significantly more information than any one technique on its own.

Landslides in the Thompson River valley, British Columbia, Canada, have historically impacted vital transportation infrastructure, the environment and natural resources, cultural heritage features, communities, public safety, and the economy. To better understand and manage geohazard risks in Canada’s primary national railway corridor, government agencies, universities, and railway industry partners are focusing research efforts on Ripley Landslide, 7 km south of Ashcroft. Electrical resistivity tomography (ERT) datasets collected in November 2013 (on land) and November 2014 (over water) were successfully combined and inverted into a pseudo-3D model that produced significantly deeper resistivity values than previously available in 2D profiles. The lithology, degree of saturation, porosity, presence of dissolved electrolytes, and temperature all influence electrical resistivity of earth materials in the landslide. Continuous (real-time) ERT monitoring began in November 2017 to characterize the long-term hydrological behavior of geological units in the landslide. Seventy-two electrodes were positioned in two arrays across the slide body and connected to a proactive infrastructure monitoring and evaluation (PRIME) system with internet access. PRIME resistivity results corroborate data from other geophysical techniques and hints at an unusual distribution pattern for surface moisture and groundwater in fractured bedrock and overlying clay-rich sediments containing vertical tension cracks and discrete sub-horizontal planar features interpreted as slide surfaces within pre-sheared zones. A greater understanding of the composition and internal structure of slope failures in the valley is gained at the site from terrain analysis and modeling of multi-dimensional geophysical datasets. This insight helps with the interpretation of multi-year monitoring datasets and will guide future efforts to record landslide activity in the valley, reducing stakeholder risks.

Resilient railway transportation networks require sustainable, cost-effective management of service operations to meet future socio-economic needs and ensure the protection of the natural environment. Where transportation corridors traverse unstable terrain, critical rail infrastructure is at risk of damage and presents potential local and national economic, social and environmental challenges. Remote monitoring of unstable slopes and infrastructure at risk, using a range of conventional and emerging fixed and automated (i.e. remote) technologies provides the fundamental geoscience required to monitor landslides along a strategically important section of Canada’s national railway network in south-central British Columbia, Canada. Research and development by the Geological Survey of Canada and British Geological Survey provides government agencies, university partners and the national railway companies with vital information to understand geohazard risk, predict landslide movement, improve the safety, security and resilience of national transportation infrastructure, and reduce such risks to the economy, environment, natural resources and public safety.

The cyclic fluctuations of matric suction and its influence on unsaturated soil mechanics in the active zone is largely disregarded in many slope stability calculations. However, the depth of the unsaturated zone can be significant, especially in semi-arid to arid climates where large portions of the slope are not governed by saturated soil mechanics. Additional tools are used to characterize historical climate and compare several factors that have resulted in changing landslide movement rates and magnitude. Infiltration of precipitation and snowmelt directly contributes to matric suction losses in the head scarp and is exacerbated by the presence of tension cracks. While groundwater levels are primarily correlated to changing movement rates in the Thompson River valley, seasonal changes in matric suction can influence the degree to which movement rates change. Climatic events and trends over the past few years alter the long-term soil water accumulation in the valley. By accounting for the additional strength or potentially rapid losses in strength due to increasing water content, it may be possible to develop a more complete understanding of the climate change mechanisms driving changing movement rates in the translational, metastable earthen slides that dominate the Thompson River valley.

Here we describe the development of a novel characterization and monitoring technology for unstable natural and engineered slopes. The system is based on time-lapse electrical resistivity tomography (ERT), which is a geophysical technique used to non-invasively image subsurface resistivity to depths of tens of meters. Resistivity is a useful property because it is sensitive to compositional variations, changes in moisture content, and ground movement. We have developed a low-cost system designed for remote operation, allowing resistivity images to be captured automatically and streamed via a web interface. It comprises four key elements: (1) low-power field instrumentation; (2) data telemetry and storage; (3) automated data processing; (4) and web dashboard information delivery. These elements form the basis of slope condition monitoring approach that provides near-real-time spatial information on both subsurface processes and surface responses. The use of this approach is illustrated with reference to the Ripley Landslide, a case study that demonstrates this approach as a means of spatially tracking complex subsurface moisture driven processes that would be very difficult to characterize using other approaches (e.g. surface observations or intrusive sampling). We propose that this approach could provide sub-surface information in the context of slope-scale landslide early warning systems.

This paper presents a novel approach to continuously monitor very slow-moving translational landslides in mountainous terrain using conventional and experimental differential global navigation satellite system (d-GNSS) technologies. A key research question addressed is whether displacement trends captured by a radio-frequency “mobile” d-GNSS network compare with the spatial and temporal patterns in activity indicated by satellite interferometric synthetic aperture radar (InSAR) and unmanned aerial vehicle (UAV) photogrammetry. Field testing undertaken at Ripley Landslide, near Ashcroft in south-central British Columbia, Canada, demonstrates the applicability of new geospatial technologies to monitoring ground control points (GCPs) and railway infrastructure on a landslide with small and slow annual displacements (

The Ripley Landslide is a small (0.04 km2), slow-moving landslide in the Thompson River Valley, British Columbia, that is threatening the serviceability of two national railway lines. Slope failures in this area are having negative impacts on railway infrastructure, terrestrial and aquatic ecosystems, public safety, communities, local heritage and the economy. This is driving the need for monitoring at the site, and in recent years there has been a shift from traditional geotechnical surveys and visual inspections for monitoring infrastructure assets toward less invasive, lower cost, and less time-intensive methods, including geophysics. We describe the application of a novel electrical resistivity tomography system for monitoring the landslide. The system provides near-real time geoelectrical imaging, with results delivered remotely via a modem, avoiding the need for costly repeat field visits, and enabling near-real time interpretation of the four-dimensional electrical resistivity tomography data. Here, we present the results of the electrical resistivity tomography monitoring alongside field sensor-derived relationships between suction, resistivity, moisture content and continuous monitoring single-frequency Global Navigation Satellite System stations. Four-dimensional electrical resistivity tomography data allows us to monitor spatial and temporal changes in resistivity, and by extension, in moisture content and soil suction. The models reveal complex hydrogeological pathways, as well as considerable seasonal variation in the response of the subsurface to changing weather conditions, which cannot be predicted through interrogation of weather and sensor data alone, providing new insight into the subsurface processes active at the site of the Ripley Landslide. © 2020 The Authors. Near Surface Geophysics published by John Wiley & Sons Ltd on behalf of European Association of Geoscientists and Engineers.

Reliable, low-cost datalogging alternatives promote transfer of knowledge and technology to the wider geotechnical and geoscientist community. Alternative systems can ease increased data resolution on large projects, operate in remote locations with restricted site access, or allow developing countries access to reliable and cost-effective datalogging solutions. A low-cost prototype datalogger was developed and tested in the laboratory with the use of open-source materials. Open-source example code is provided at the permanent links included in this paper. The materials for the prototype were 20 % the cost of commercial datalogging units with similar capabilities. With labor, these custom-built units were 35–45 % the cost of a purchased datalogger. Measurements from commercial units and the prototype datalogger were compared to determine the prototype’s accuracy. The datalogger was deployed in place of commercially available dataloggers at three sites across western Canada in the past two years. Laboratory and field testing of the low-cost datalogger has shown the prototype to be easily adaptable to various sensor types. The study experimented with negative pore water pressure (matric suction), volumetric water content, and temperatures from SDI-12 sensors as well as positive pore water pressure and temperature from vibrating wire piezometers. Telemetry modules have been attached to remote dataloggers, transmitting occasional data points, and periodically verifying system operation. Assembly, installation, and monitoring with the low-cost datalogging system over the past two years has demonstrated their durability in field applications. The implementation of a low-cost, open-source geotechnical datalogging system can be a challenge in some locations and requires the consideration of limitations, which are addressed.

The Thompson River valley, south of Ashcroft in British Columbia, Canada, has experienced several landslides since the mid-1800s. The national railways that run along the valley cross a number of these landslides. All the landslides occur in glacial deposits, typically sliding on weak clay layers. Some have failed rapidly to very rapidly and are currently inactive or showing deformation rates from a few millimeters to centimeters per year. An evaluation of satellite InSAR (Interferometric Synthetic Aperture Radar) using RADARSAT-2 images between September 2013 and November 2015 provides new insight into landslide displacements in the Thompson River valley. This information enhances the ongoing hazard management of unstable terrain. This paper presents the comparison of the InSAR measurements with other instrumentation (GPS and ShapeAccelArrays™ -SAA) installed at one moving landslide and then addresses the extent and magnitude of the slope movements observed. InSAR was found to provide similar displacement values to those measured otherwise. The stable location showed displacements of +/−1 mm with an average near zero during the whole monitoring period. Six areas of slope movement were identified within the study area, all within or adjacent to the footprints of past landslides. The average line of sight (LOS) displacement rates range between 11 and 39 mm/year. Most of the landslides exhibited seasonal variations in velocity that corresponds to changes in river elevation in the valley.

Electrokinetic geosynthetics enable civil engineers to put electrical energy into the ground to stiffen it and control groundwater flows. This paper summarises the evolution of the technology over the past 25 years, from research by way of hype and into practice. It was conceived in 1993 at Newcastle University in the UK, combining established knowledge of geotextiles with historical studies of electrokinetics. A series of UK government-funded research programmes helped to generate global interest in its possible applications, leading to a technology spin-off company being incorporated in 2001 to attract private venture capital investment and further development funding. This eventually narrowed down the practical applications to slope stabilisation and dewatering, which now form the company’s main revenue streams.

This paper reports on the landform assemblages at the northern confluence of the Late Wisconsinan Laurentide and Cordilleran ice sheets with montane and piedmont glaciers in the northern Rockies and southern Mackenzie Mountains. Recent observations in northeastern British Columbia refine our knowledge of the pattern and style of ice sheet retreat, glacial lake formation, and meltwater drainage. At the onset of deglaciation, confluent Laurentide and Cordilleran terminal ice margins lay between 59°N, 124°30′W and 60°N, 125°15′W. From this terminal limit, ice sheets retreated into north-central British Columbia and Yukon Territory, with remnant Cordilleran ice and montane glaciers confined to mountain valleys and the Liard Plateau. Distinctive end moraines are not associated with the retreat of Cordilleran ice in these areas. Laurentide ice retreated northeastward from uplands and the plateaus; then separated into lobes occupying the Fort Nelson and Petitot river valleys. Ice-retreat landforms include recessional end moraines (sometimes overridden and drumlinized), hill–hole pairs, crevasse-fill deposits, De Geer-like ribbed till ridges, hummocky moraines, kames, meltwater features, and glacial lake deposits that fall within the elevation range of glacial Lake Liard and glacial Lake Fort Nelson (ca. 840–380 m). Meltwater and sediment transport into glacial lakes Fort Nelson, Liard, Nahanni, and Mackenzie was sustained by remnant ice in the Liard River and Fort Nelson River drainage basins until the end of glaciation. Optical dating of sand from stabilized parabolic dunes on the Liard Plateau indicates that proglacial conditions, lake formation, and drainage began before 13.0 ± 0.5 ka (calendar years). The Petitot, Fort Nelson, and Liard rivers all occupy spillways incised into glacial deposits and bedrock by meltwater overflow from glacial lakes Peace and Hay.

To fully understand tsunami hazards along Canada’s Pacific coast we must consider all potential sources including local and region-wide earthquakes, volcanic activity, slope failure events and bolide impacts. Furthermore, as climate changes, future extreme meteorological conditions will exacerbate slope failures on steep and over-steepened slopes, and potentially augment the magnitude and frequency of earthquake-generated tsunamis. There have been numerous reviews of the geological records of palaeotsunamis along the Cascadia margin, but as yet there has been no attempt made to pull together all data related to palaeotsunamis along the Pacific coast of Canada. We summarise all geological data related to palaeotsunamis reported in the region, all relevant non-geological data, and other information concerning potential tsunamigenic sources. Evidence for between 10 and 22 palaeotsunamis (prior to European arrival) have been documented, with the Cascadia Subduction Zone Y event (AD1700) being the most widely recognised. Geological, archaeological and anthropological data all indicate a complex, multi-sourced, prehistory of seismic/tsunami activity that is poorly understood. A clustering of potential activity off the SE coast of Vancouver Island suggests that we should also attempt to better understand locally generated events along Canada’s Pacific coast.