Tiltmeters on Turtle Mountain

What is a Tiltmeter?

A tiltmeter is like a carpenter's level, but it uses electronics to precisely measure changes in angles. On rock slopes, tiltmeters are fixed to the sides of large blocks of rock to measure how much they rotate prior to collapse.

Tiltmeters on Turtle Mountain

There are 10 tiltmeters along the highly fractured summit ridge area near South Peak. These instruments have a resolution of about 10 arc seconds or 0.05 mm/m.

We connected the tiltmeters by cable to a datalogger, which reads them before telemetering the data back to the Frank Slide Interpretive Centre. Readings are taken hourly. The datalogger/telemetry system is also used by the surface extensometer system.

Results

We have seen a variety of different trends on the tiltmeter network. These range from sensor fluctuations, mirroring the temperature cycles, to trends that may point to cumulative, permanent creep observed on two of the sensors.

We can see seasonal changes in tilt, and in general, all sensors display an increase in tilt at the beginning of summer and a return to the previous trend at the beginning of autumn. A similar cyclic variation in tilt occurs with daily temperature changes, but at a smaller scale (~ 0.01°C). Noisy responses due to moisture in the sensors continue to affect the quality of tiltmeter data (T-1, T-8 and T- 10); however, adding desiccant packs in summer 2006 remarkably improved data quality (T-2 and T-3).

Plot of tilt versus time for tiltmeters at the south peak of Turtle Mountain. Click on graph to enlarge.

Tiltmeters on Turtle Mountain. Click on images to enlarge.