The exhibition Nature Unleashed, now showing at the museum, explores the forces of nature through natural disasters. For many employees of the museum, the exhibition also recalls a local earthquake of a couple of years ago.
First came the rumble of noise and motion. And then, the lights started shaking. That’s when they knew it was an earthquake.
When the magnitude 5.0 quake struck the museum’s massive stone building in late June 2010, it also rattled many of the staff—both literally and metaphorically.
Fortunately, no-one was hurt and physical effects were minor. One staff member was left dizzy from the 30 seconds of movement and the sight of walls shaking around him. Another staffer on the top floor (where the movement was greatest) felt ill and had trouble regaining her balance for the next half hour.
Emotional balances also took a hit, and for some, the upset lingered. Acutely aware of the exposed lighting grids overhead, the reputation of masonry for breaking not bending, and the deposit of unstable Leda clay lurking directly under the building, some staff were a bit scared, while others were terrified. A former San Franciscan found it more exciting than frightening. Visitors seemed to generally take it in stride; some stepped outside, while others simply rode it out.
Although they didn’t know it at the time, the 100-year-old building had never experienced an earthquake this large. Indeed, the shaking was the strongest that Ottawa has experienced in the last 200 years, if not ever.
The timing could not have been better. It had been only 32 days since the museum’s grand reopening following renovations that were undertaken to install a steel skeleton inside the stone walls as reinforcement against earthquakes.
The risk was very real. Leda clay’s high water content makes it prone to liquefying when disturbed, such as by larger earthquake vibrations. Even without tremors, the clay had been causing significant problems because the weight of all that stone doesn’t sit well on the clay. Uneven settling had caused cracks in walls, floors and foundations (one large enough to fit a person). It also proved fatal to the original tower: by 1915, the sinking was so great, the tower had started to pull away from the building and had to be removed.
We hate to think what could have happened had the earthquake struck before the structural upgrade, but as it was, the museum got off lightly. As for the building, only a few superficial cracks formed in walls near archways. Among the exhibits, almost 30 minerals were knocked over or jostled, some bird eggs rolled off their nests, a leg and a head of two taxidermy mounts were almost broken off, and a mineral broke. Fortunately, all could be mended, and the almost-invisible mineral repair actually improved on an earlier fix.
One staff member also came out the better for it. He’d always been nervous about the building’s situation, so when the quake came, it was a kind of test for him. It was such a relief that the engineering of the retrofit really worked, it allowed him to let go of his concerns. “It was an important day in my life because the construction was long, and we saw the results.”
The study of earthquakes is not part of the museum’s research programme, but in 2003, the Geological Survey of Canada installed monitoring equipment in our sub-basement. The device is called an Etna station and it measures acceleration in ground movement. (Seismographs, by contrast, measure velocity). Read the official reports on the earthquake.
And, you can learn more about earthquakes in the special exhibition Nature Unleashed, at the museum until May 4, 2013. The section on earthquakes features some real doozies, such as the Great San Francisco Earthquake of 1906. Our moderate earthquake is definitely not in the same category!