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TitleMonitoring deformation at the Frank Slide from InSAR techniques
AuthorSinghroy, V; Molch, K; Couture, R
SourceProceedings of the International Consortium on Landslides symposium: extended abstracts volume; 2003 p. 45-46
Alt SeriesEarth Sciences Sector, Contribution Series 2005039
MeetingInternational Consortium on Landslides symposium, 2nd Annual Meeting; Vancouver; CA; October 30, 2003
AreaFrank; Turtle Mountain; Crowsnest Pass
Lat/Long WENS-114.5000 -114.0000 49.7500 49.5000
Subjectssurficial geology/geomorphology; landslides; deformation; satellite imagery; remote sensing; slope stability analyses; interference patterns; displacement; flow structures; limestones; flow mechanisms; Frank Slide; monitoring; Paleozoic; Quaternary; Cenozoic
Illustrationsradar images; block diagrams
AbstractRemote sensing techniques are increasingly being used in slope stability assessment. (Murphy and Inkpen, 1996; Singhroy et al., 1998; Singhroy and Mattar, 2000). Recent research has shown that differential interferometric SAR techniques can be used to monitor landslide motion under specific conditions. (Vietmeier et al., 1999 and Rott et al.,1999). Provided coherence is maintained over longer periods, as is possible e.g. in non-vegetated areas, to observe surface displacement of a few cm per year. Using data pairs with short perpendicular baselines, short time intervals between acquisitions, and correcting the effect of topography on the differential interferogram, reliable measurements of surface displacement can be achieved.
Contrary to motion on the detachment zone, roughness and distribution of landslide debris and their post slide stability has not been studied in detail using remote sensing. This is due in part to the lack of topographic data for blocky landslides and therefore the link between debris roughness and radar backscatter (s0) has remained elusive. Roughness is defined as the topographic expression of surfaces at horizontal scales of centimetres to a few hundred meters. Landslide surface structures and roughness provide information on flow emplacement parameters (such as emplacement rate, velocity, and rheology). Several investigations have focused on characterizing grain size and distribution of this rock avalanche, in order to understand post failure mechanism and mobility (Couture et al. 1998; Cruden and Hungr, 1986). Laser altimeters are used to calculate surface roughness. Digital image analyses of large-scale photographs were used to examine grain size distribution of rock avalanche debris (Couture et al., 1998). In-situ methods used to examine the statistical roughness of geologic surfaces can improve the interpretation of remotely sensed data at all wavelengths
Our study focused on the Frank Slide, a 30x (10)6m3 rockslide-avalanche of Paleozoic limestone, which occurred in April 1903 from the east face of Turtle mountain in the Crowsnest Pass region of southern Alberta, Canada. Seventy fatalities were recorded. In this study our interferometric images show minor deformation along parts of the geological structure, suggesting that the slide may still be active. These findings may assist in targeting current in-situ motion detectors. The textural analysis of the high resolution RADARSAT image provide an accurate characterization of the debris size and distribution, suggesting that SAR image texture is a useful parameter to map the distribution of slide debris. These remote sensing techniques will assist in the understanding of landslide processes, post failure mechanism and mobility.

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