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TitleStructural analysis of Turtle Mountain (Alberta) using digital elevation model: Toward a progressive failure
AuthorJaboyedoff, M; Couture, R; Locat, P
SourceGeomorphology vol. 103, issue 1, 2009 p. 5-16,
Alt SeriesEarth Sciences Sector, Contribution Series 20110015
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf (Adobe Acrobat Reader)
Areasouthwestern Alberta; Canadian Rocky Mountains; Turtle Mountain; Frank
Lat/Long WENS-144.5000 -114.0000 49.7500 49.5000
Subjectsengineering geology; structural geology; landslides; landslide deposits; slope stability; slope failures; rock mechanics; mass wasting; debris flow deposits; Frank Slide
Illustrationslocation maps; diagrams; plots; tables; cross-sections; stereonets
ProgramReducing Risk from Natural Hazards
AbstractIn 1903, the eastern slope of Turtle Mountain (Alberta) was affected by a 30 M m3-rockslide named Frank Slide that resulted in more than 70 casualties. Assuming that the main discontinuity sets, including bedding, control part of the slope morphology, the structural features of Turtle Mountain were investigated using a digital elevation model (DEM). Using new landscape analysis techniques, we have identified three main joint and fault sets. These results are in agreement with those sets identified through field observations. Landscape analysis techniques, using a DEM, confirm and refine the most recent geology model of the Frank Slide. The rockslide was initiated along bedding and a fault at the base of the slope and propagated up slope by a regressive process following a surface composed of pre-existing discontinuities. The DEM analysis also permits the identification of important geological structures along the 1903 slide scar.

Based on the so called Sloping Local Base Level (SLBL) an estimation was made of the present unstable volumes in the main scar delimited by the cracks, and around the south area of the scar (South Peak). The SLBL is a method permitting a geometric interpretation of the failure surface based on a DEM.
Finally we propose a failure mechanism permitting the progressive failure of the rock mass that considers gentle dipping wedges (30°). The prisms or wedges defined by two discontinuity sets permit the creation of a failure surface by progressive failure. Such structures are more commonly observed in recent rockslides. This method is efficient and is recommended as a preliminary analysis prior to field investigation.

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