May 27, 2012 was an unusually hot and sticky spring day. A severe thunderstorm rumbled over London and south across Lake Erie toward Ohio just after 1 p.m.The mercury topped out at 31C and skies quickly cleared. Beaches near Cleveland came alive with sun-seekers and swimmers. It was the Memorial Day long weekend.But by late afternoon the weather office was fielding urgent telephone calls from alarmed citizens.“People saw three seven-foot waves, out of nowhere,” says Eric Anderson, an oceanographer with the U.S. National Oceanic and Atmospheric Administration in Ann Arbor, Mich.A trio of swimmers in Madison, 40 minutes east of Cleveland, was swept almost a kilometre into the lake and later rescued. A marina was swamped.These were no ordinary waves. They were a type of tsunami known as a meteotsunami.Anderson was one of 25 experts who met this week at the University of Michigan Co-operative for Great Lakes Research to devise an early-warning system for the planet’s largest fresh water system, which has 16,000 kilometres of coastline.“The risk is always higher if you have not prepared for anything,” says Chin Wu, an engineering professor at the University of Wisconsin.“It’s not a big problem in the deep part of the lake, until you reach the shore where the water will be shallower, and it will always pump up the tsunamis.”Unlike regular tsunamis caused by earthquakes, such as the 2011 wave that devastated parts of Japan, meteotsunamis are caused by meteorological conditions, specifically, fast-moving convective storms with enough power to push water down and ahead of them akin to a tidal surge.In a research paper published last year, Anderson, Wu and several co-authors warn “meteotsunamis may become even more frequent under a changing climate” with fiercer storms.“Generally, they’re not as destructive as earthquake tsunamis, but they can surprise you,” says Anderson, a Pennsyl ...
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