Abstract | The magnitude (Mw) of 5.0 Val-des-Bois earthquake that occurred in Quebec on June 23, 2010 was the biggest recent earthquake in eastern Canada. It produced the strongest shaking ever felt in Ottawa. The ground shaking was widely felt in Ontario and Quebec, and it was also felt in the US as far as Kentucky. A number of records from this event were compiled and processed by the Geological Survey of Canada. Of special importance for this paper are the recorded vibrations of three towers of the Parliament Hill buildings in Ottawa, i.e., the Peace Tower of the Centre Eilock, the Mackenzie Tower of the West Block, and the South-West Tower of the East Block. In total 27 records were obtained at the towers, including records at the ground level, at the middle and at the top of the towers. These are the first significant records obtained on the towers during an earthquake. The records were processed to determine the dynamic characteristics of the towers. Based on the Fourier amplitude spectra of the recorded signals, the natural frequencies of the vibration modes were determined. These were found to be very similar to those from ambient vibration tests. The results from this study are very important for seismic evaluations of the towers on Parliament Hill. |
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