Seiches, small but often destructive and sometimes fatal tidal waves, hit Chicago about once every ten years, and reach heights of over ten feet.

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A seiche starts much the same way waves in a bathtub do, or ripples on your coffee when you blow on it to cool. A strong wind starts a little wave, and the wave gets bigger. Then, when the water hits the other side of the lake, it bounces back, where it starts to grow bigger. There is almost no way to predict seiches, but since the most fatal seiche in Chicago history in 1954, during which eight people drowned, many small improvements have been made to the safety for those on land.