| Title | Combining terrestrial and waterborne geophysical surveys to investigate the internal composition and structure of a very slow-moving landslide near Ashcroft, British Columbia, Canada |
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| Author | Huntley, D ;
Bobrowsky, P; Best, M |
| Source | International Consortium on Landslides 4th World Landslide Symposium; 2017 p. 179-190, https://doi.org/10.1007/978-3-319-53498-5 21 |
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| Year | 2017 |
| Alt Series | Earth Sciences Sector, Contribution Series 20160236 |
| Publisher | Springer International Publishing |
| Meeting | International Consortium on Landslides 4th World Landslide Symposium (WLF4); Ljubljana; SI; May 29 - June 2, 2017 |
| Document | book |
| Lang. | English |
| Media | paper; on-line; digital |
| Province | British Columbia |
| NTS | 82E; 82F/03; 82F/04; 82F/05; 82F/06; 82F/11; 82F/12; 82F/13; 82F/14; 82K/03; 82K/04; 82K/05; 82K/06; 82K/11; 82K/12; 82K/13; 82K/14; 82L; 82M; 82N/03; 82N/04; 82N/05; 82N/06; 82N/11; 82N/12; 82N/13; 82N/14;
92F; 92G; 92H; 92I; 92J; 92K; 92N; 92O; 92P |
| Area | Ashcroft |
| Lat/Long WENS | -126.0000 -117.0000 52.0000 49.0000 |
| Subjects | engineering geology; geophysics; sedimentology; soils science; surficial geology/geomorphology; landslides; ground probing radar; seismic surveys, ground; gravity surveys, ground; resistivity surveys,
ground; magnetic surveys, ground; clays; tills; silts; conductivity surveys; seismic refraction surveys; mapping techniques |
| Illustrations | satellite imagery; satellite images; location maps; tables; photographs; stratigraphic cross-sections; structural diagrams |
| Program | Public Safety
Geoscience Marine Geohazards |
| Released | 2017 06 11 |
| Abstract | A vital section of Canada¿s national railway transportation corridor traverses a 7 km-long section of unstable terrain in the Thompson River valley, British Columbia. Landslides in this region have
adversely impacted vital national railway infrastructure and operations, the environment, cultural heritage features, communities, public safety and economy since the late 19th Century. To help manage the potential risks associated with railway
operations across this active slide zone, field investigations and monitoring of a very slow-moving Ripley Landslide are being undertaken by a consortium of research partners from government, academia and industry. Knowledge of the internal
composition and structure of the landslide as interpreted through surficial geology mapping and geophysical surveys provide contextual baseline data for interpreting monitoring results; in addition to understanding mass-wasting processes in the
Thompson River transportation corridor. Bathymetry, electrical resistivity tomography, frequency-domain electromagnetic terrain conductivity, ground penetrating radar, seismic refraction, multi-spectral surface wave analyses, and borehole logging of
natural gamma, conductivity and magnetic susceptibility all suggest a moderately high relief bedrock sub-surface overlain by a >20 m thick package of clay, silt, till diamicton, gravel containing groundwater. Planar physical sub-surface features
revealed in geophysical profiles and logs include tabular bedding and terrain unit contacts. Field observations and geophysical profiles also show curvilinear-rectilinear features interpreted as sub-horizontal translational failure planes in
clay-rich beds beneath the rail ballast and lock-block retaining wall at depths between 5 m and 15 m below the surface of the main landslide body. The landslide toe extends under the Thompson River where clay-rich sediments are confined to a >20 m
deep bedrock basin. The upper clay beds are armoured from erosion by a lag deposit of modern fluvial boulders except along the west river bank where a deep trough has been carved by strong currents. High waterborne conductivity levels indicate
discharge of groundwater through the boulder lag. Fluvial incision of the submerged toe slope at the south end of the landslide is observed <50 m west of where critical railway infrastructure is at risk. Integrating data from surficial geology
mapping and an array of geophysical techniques provided significantly more information than any one method on its own. |
| Summary | (Plain Language Summary, not published)
A vital section of Canada's national railway transportation corridor traverses a 7 km-long section of unstable terrain in the Thompson River valley,
British Columbia. Landslides in this region have adversely impacted vital national railway infrastructure and operations, the environment, cultural heritage features, communities, public safety and economy since the late 19th Century. Integrating
data from surficial geology mapping and an array of geophysical techniques provided significantly more information than any one method on its own. |
| GEOSCAN ID | 299369 |
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