Open File Report 2008-07

Open File Report 2008-07

OFR 2008-07

Turtle Mountain Field Laboratory: 2007 Data and Activity Summary

Author(s) Moreno, F. Froese, C.R. Date 2008-12-02

This report provides the 2007 annual summary of results and interpretations for the benefit of the geotechnical community and stakeholders in the Crowsnest Pass. The report is meant to be brief, with the more detailed scientific results being presented in peer-reviewed journals and conference publications.

Since 2005, Alberta Geological Survey has reviewed 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 South Peak site has been termed the Turtle Mountain Field Laboratory (TMFL because the data from the sensor network at the site will 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.

Near-real time data continue to show trends corresponding with both seasonal thermal cycles and with slow, long-term creep of the South Peak mass. In general, the trends observed highlighted very slow movement along the deep fractures to the west side of South Peak at less than a millimetre per year. Preliminary results from detailed mapping of Third and South peaks, including lower slopes, has helped to define potential zones of movement and led to interpretations as to mechanisms for movement and potential volumes involved in these areas.

During 2007, a network of periodically read GPS monuments was installed on the more active portions of the peak highlighted by photogrammetry studies. In addition, the differential global positioning systems (dGPS) and electronic distance measurement (EDM) system installation was completed. This included the addition of a number of new prisms on the eastern face of South Peak and lower down the mountain. This will allow gathering a more complete picture of the pattern of movement in potentially unstable areas.

Reliability and continuity of the monitoring system have been reasonable and are 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 carried out to increase the reliability of the sensor network. Similar efforts, although possibly diminishing, will likely be necessary in future. Continued work is planned to upgrade and maintain the monitoring system, this includes maintenance of the roof system for the crackmeters, continued protection of the tiltmeters against humidity and replacement of faulty instruments.

Moreno, F. and Froese, C.R. (2008): Turtle Mountain field laboratory: 2007 data and activity summary; Energy Resources Conservation Board, ERCB/AGS Open File Report 2008-07, 40 p.