Strong motion seismographs are instruments that stay on-scale when shaking caused by an earthquake is strong enough to exceed the recording ability of the seismographs typically used to locate earthquakes.
In Canada, the first strong motion seismograph was manufactured and installed in1963, in Victoria, British Columbia and triggered a new direction in earthquake studies in Canada that focused on measuring and understanding the effects of earthquakes. There are now over 300 strong motion seismographs used in Canada by various agencies, with almost half by the Geological Survey of Canada.
These seismographs are deployed where strong shaking might occur, and most are located in urban areas or adjacent to critical infrastructure. Their recordings provide valuable input for engineering design, for assessing the magnifying effects of local geology on shaking, and for knowledge of the level of local shaking immediately after an earthquake.
One of the largest accelerations from earthquake shaking ever recorded (over twice the acceleration of gravity) was recorded near a magnitude 6.9 earthquake in the Nahanni region of the Northwest Territories by a temporarily deployed strong motion seismograph.
Category: Equipment and Instrumentation
Cassidy, J.F., Rogers, G.C., Adams, J., and Halchuk, S., 2015. Canadian strong motion monitoring and recent datasets from Natural Resources Canada; Proceedings, 11th Canadian Conference on Earthquake Engineering, 21–24 July 2015, Victoria, Canada, Paper 93832, 10 p.
Rogers, G.C., Milne, W.G., and Bone, M.N., 1970. The strong motion seismograph network in western Canada - 1970; Publications of the Earth Physics Branch, Ottawa, v. 41, p. 1–29.