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In 1981, an Alberta Government project upgraded the monitoring of South Peak, Turtle Mountain, on the south margin of the 1903 Frank Slide. The monitoring program aimed at understanding the rates of deformation over large, deep fractures encompassing South Peak and predicting a second large rock avalanche on the mountain. The monitoring program consisted of a complement of static ground points and remotely monitored targets measured periodically, and climatic, microseismic, and deformation data collected automatically on daily intervals and archived. In the late 1980s, developmental funding for the monitoring program ceased and some of the installations fell into disrepair. Between May 2004 and September 2006, readings from the remaining functional monitoring points were compiled and interpreted. In addition, readings compiled previously were re-interpreted based on a more recent understanding of short-term movement patterns and climatic influences. These observations were compared with recent observations from an airborne light detection and ranging (LIDAR) digital elevation model and field photographs to give more precise estimates of the overall rates, extent, and patterns of motion for the past 25 years. Key words: Turtle Mountain, geological structure, light detection and ranging (LIDAR), monitoring, digital elevation model (DEM). En 1981, le gouvernement de l'Alberta a ameliore la surveillance de la pointe sud << South Peak >> de la montagne Turtle, sur la frontiere sud du glissement Frank de 1903. Le programme de surveillance vise a comprendre les taux de deformation des fissures larges et profondes sur << South Peak >>, et a predire une seconde avalanche rocheuse sur la montagne. Le programme de surveillance consiste a installer un complement de points statiques et de stations suivies a distance, qui sont mesures periodiquement. Des donnees climatiques, microsismiques et de deformation sont recueillies automatiquement a intervalles journaliers, et sont archivees. A la fm des annees 1980, le financement pour le developpement du programme de surveillance a cesse et quelques installations se sont deteriorees. Entre mai 2004 et septembre 2006, des lectures sur les points de surveillance encore fonctionnels ont ete compilees et interpretees. De plus, les lectures prelevees auparavant ont ete reinterpretees a partir des connaissances recentes sur les modeles de mouvement a court terme et les influences climatiques. Ces observations ont ete comparees a des recentes observations aeriennes d'un modele digital d'elevation, provenant de << light detection and ranging (LIDAR) >>, et des photos de terrain, afin d'estimer plus precisement les taux, l'etendue et la distribution des mouvements pour les derniers 25 ans. Mots-cles : Montagne Turtle, structure geologique, << light detection and ranging (LIDAR) >>, surveillance, modele d'elevation numerique << DEM >>. [Traduit par la Redaction], Introduction At 0410 on 29 April 1903, 30 x [10.sup.6] [m.sup.3] of limestone on the east face of Turtle Mountain (Fig. 1) moved rapidly into the Crowsnest Pass below. Over [...]

Abstract: The Frank Slide occurred on the east limb of the Turtle Mountain Anticline, which was thrust up along the folded and splayed Turtle Mountain Fault. Easterly dipping, Paleozoic limestones [...]

Rock falls represent a large percentage of landslide-related hazards reported by Canadian railways in mountainous terrain. A 54.7 km-long section of railway through the Canadian Cordillera is examined that experiences, on average, 18 rock falls each year. An approach for rock fall hazard management is developed based on quantified risk. The approach focuses on defining railway operation procedures (freight train operations and track maintenance) that comply with quantified risks. Weather-based criteria that define periods when rock falls are more likely to occur along the study area are examined. These criteria are used herein to reduce exposure to rock falls and reduce their consequences. Several freight train operation strategies are proposed that comply with a tolerable level of risk adopted in this study for illustrative purposes. The approach provides a simple, flexible and practical strategy for railway operations that can be regularly adopted by the operators, and that is based on a more comprehensive assessment of quantified risk. [ABSTRACT FROM PUBLISHER]

Relationships between weather conditions and rock fall occurrences have been acknowledged in the past, but seldom have such relationships been quantified and published. Rock falls are frequent hazards along transportation corridors through mountainous terrain, and predicting hazardous rock fall periods based on weather conditions can enhance mitigation approaches. We investigate the relationship between weather conditions and rock fall occurrences along a railway section through the Canadian Cordillera. Monthly weather-rock fall trends suggest that the seasonal variation in rock fall frequency is associated with cycles of freezing and thawing during the winter months. The intensity of precipitation and freeze–thaw cycles for different time-windows was then compared against recorded rock falls on a case-by-case approach. We found that periods when 90% of rock falls occurred could be predicted by the 3-day antecedent precipitation and freeze–thaw cycles. Some rock falls not predicted by this 3-day antecedent approach occurred during the first two weeks of spring thaw. These findings are used to propose a rock fall hazard chart, based on readily available weather data, to aid railway operators in their decision-making regarding safe operations. [ABSTRACT FROM PUBLISHER]

Slopes in weakly cemented glaciolacustrine sediments in the Morkill River valley in the Canadian Rocky Mountains stand at up to 70°. Based on field and laboratory observations it appears that a contributing factor to instability is the softening of the soils by frost action and the leaching of calcite cement. Field density profiles demonstrated increased density and carbonate content with an increase in depth. Laboratory tests of carbonate content indicated a positive correlation between calcium carbonate and density in the glaciolacustrine sediments. The relationship was strongest in sands, in which leaching and dissolution were important components of softening. In clays, frost action was the dominant component of softening. Freeze-thaw tests showed a 50% decrease in strength after one cycle of freeze and thaw in the silts and clays.Key words: landslide, cemented, glaciolacustrine sediments, British Columbia.Les pentes dans les sédiments glaciolacustres dans la vallée de la rivière Morkill dans les montagnes Rocheuses canadiennes tiennent jusqu'à des angles de 70°. D'après des observations sur le terrain et en laboratoire, il semble qu'un facteur qui contribue à l'instabilité est le ramollissement des sols par l'action du gel et le lessivage du ciment de calcite. Les profils de densité du terrain ont montré une densité et une teneur en carbonate croissantes avec la profondeur. Des essais de teneur en carbonate en laboratoire ont indiqué une corrélation positive entre le carbonate de calcium et la densité dans les sédiments glaciolacustres. La relation était plus marquée dans les sables dans lesquels le lessivage et la dissolution étaient des composantes importantes du ramollissement. Des essais de gel-dégel ont montré une diminution de 50 % de la résistance après un cycle de gel et dégel dans les silts et les argiles.Mots clés : glissements de terrain, cimenté, sédiments glaciolacustres, Colombie Britannique.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]