Analysis of Modern Landslide Deformations in the Thompson River Valley using InSAR

  • Author / Creator
    Journault, Jeffrey B
  • The slow movement of historic landslides is a constant reality in the Thompson River Valley, with twelve such slides located within ten kilometers of the town of Ashcroft, B.C. alone. Beginning at the end of the 19th century, numerous rapid slope failures were reported by local residents and the two major Canadian railways occupying the corridor, Canadian Pacific (CP) and Canadian National (CN). These reports continued sporadically into the 20th century, with the most recent rapid failure occurring at the Goddard Slide in 1982. Today, slope movements in the Ashcroft area are more subdued, consisting primarily of slow displacements along established failure surfaces within or adjacent to historic landslide footprints. The large spatial extent of the Thompson Valley and of most landslides contained within it has obliged railway operators to focus monitoring and investigative resources to the most active areas of instability. As part of this optimization effort, a small yet relatively active site, the Ripley Slide, was established as a research site for programs aimed at better understanding the mechanisms of instability within the corridor. This “field laboratory” has since supported a wide variety of geoscience research activities, ranging from material characterization, groundwater sampling, to a host of geophysical studies. With the mechanisms of instability at the Ripley site becoming better understood, motivation has shifted to applying the lessons learned at Ripley to the other landslides in the area. In tandem with this shift, remote-sensing technologies have evolved and moved to the forefront of geotechnical science, largely due to their capacity to measure ground surface deformations over wide areas with great accuracy while at the same time requiring little to no ground-based equipment or works. Synthetic Aperture Radar Interferometry, or InSAR, is one such technology that has enabled researchers to expand geotechnical studies to the entire Ashcroft corridor. Natural Resources Canada (NRCan) began acquiring radar images of the Thompson River Valley in 2011 using RADARSat-2, a Canadian Space Agency (CSA) satellite launched in late 2007 to replace the older RADARSat-1. In fall 2015, an interferometric analysis of the SAR images acquired up to that time was carried out using Persistent Scatterer Interferometry, or PSI. This work presents a summary of the PSI analysis results, along with a review of landslide activity within Thompson Valley, a discussion of the technical background of InSAR, as well the validation of PSI results based on existing instrumentation data. In total, six zones of active ground deformation located within existing or historic landslide footprints are identified and discussed. The most active of these are the Ripley and Red Hill slides, both of which express clear seasonal variations in all PSI datasets. Following these in terms of deformation activity are the Goddard Toe, South Extension, and North Slide Toe. Finally, the Barnard slide has been identified as the least active AOI within the study area, showing subdued yet steady deformation over time.

  • Subjects / Keywords
  • Graduation date
    Spring 2017
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.