Seiche?

After a spell of stormy weather, the surface of Lake Michigan was calm off the shore near Holland, Mich., one sunny, windless day last week. Without warning a huge, smooth wall of water, at least ten feet high according to witnesses, rolled in from the lake, smashed the shoreline. Other big waves followed. Scores of rescues were made along miles of waterfront. Five persons were swept out into the lake by a ferocious undertow and drowned.

The question for meteorologists and geologists was, what caused this wall of water which, if it had occurred at sea, would have been called a "tidal wave"? Engineers of the U. S. Lake Survey at Detroit advanced several hypotheses. One was that the wave had been kicked up by a high wind or thundersquall in midlake.

Best guess, however, seemed to be that the disturbance was a seiche (pronounced saysh)--that is, an oscillation in the water caused by an area of rising barometric pressure adjoining an area of falling pressure. The pressure difference would create a sort of hill and valley in the lake surface, and the big wave with its followers would result from the water's effort to resume a horizontal surface. A similar seiche, subsequently described scientifically in Naval Institute Proceedings, rose in Lake Erie off Cleveland some years ago, caused several deaths.

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