Earth Sciences Report 2006-07

Earth Sciences Report 2006-07

ESR 2006-07

Turtle Mountain Field Laboratory Monitoring and Research Summary Report, 2005

Author(s) Moreno, F. Froese, C.R. Date 2006-11-01

Since 2005, the Alberta Geological Survey has undertaken detailed review of the near real-time data stream from a sensor network installed on the South Peak of Turtle Mountain and initiated numerous supporting studies to better understand the style and rate of movement of the slowly moving rock mass. The site itself has been termed the Turtle Mountain Field Laboratory, as it is intended that the data from the sensor network and the site itself be used by the international geotechnical research community to develop a better understanding of the mechanics of slowly moving rock masses, instrumentation for measuring these movements and the application of new technologies.

Initial findings regarding the style and rate of movement at South Peak are slowly coming available and indicate it has had a long history of very slow deformation, with rates of movement of up to 3 mm/year over the past 24 years. These movements are of interest, but below levels of concern for the stability of the slope, considering the large extensions that have obviously occurred during crack formation. New results from remote-sensing techniques (photogrammetry and satellite-based Interferometric Synthetic Aperture Radar) are corroborating the movement data. Most of the net displacements for the past year are believed to be the result of the early June and September precipitation events. The total displacements shown on extensometers are considered to be indicative of the sudden movement, across the cracks that they span, associated with precipitation and cold weather. Although these extensions have not been seen in nearby crackmeters and tiltmeters, it is appropriately conservative to conclude that these records should be considered as real deformation. Additional monitoring points on the east face of South Peak are required to verify the postulated sliding surface in the BGC Engineering Inc. report and to find the relationship, if any, between crack movement and movement on the extensive sliding surface.

Reliability and continuity of the monitoring system has been reasonable for the first year of operation and is expected to improve. Current level of reliability allows the instrumentation installed at Turtle Mountain to provide an indication of increased movements on South Peak. Periodic and visual inspections have been carried out at Turtle Mountain and have proven to be a necessary and important element of the monitoring system. Considerable maintenance and repair have been required and have been carried out to increase the reliability of the sensor network. Similar efforts, although possibly diminishing, will likely be necessary in the years to come. Continued work is planned to upgrade and maintain the monitoring system. This includes modifying and commissioning the differential GPS and electronic distance measurement systems, upgrading the roof system for the crackmeters and improving protection of the tiltmeters against humidity.

Moreno, F. and Froese, C.R. (2006): Turtle Mountain Field Laboratory monitoring and research summary report, 2005; Alberta Energy and Utilities Board, EUB/AGS Earth Sciences Report 2006-07, 94 p.