This weird phenomenon brings tsunamis closer to home than you think

Caroline FloydMeteorologist

The word 'tsunami' can evoke some terrifying images, but did you know that tsunami waves can strike much closer to home -- even away from the ocean entirely?

A meteorological tsunami, or 'meteotsunami', is a kind of wave generated by weather conditions, rather than seismic activity. Specifically, they're generated by air pressure changes generally associated with fast-moving weather fronts or storms. While they can form in ocean waters adjacent to the shoreline, they're also frequently observed on large bodies of inland water, such as the Great Lakes.

Meteotsunami waves don't carry the energy of their more-famous cousins so their effects tend to be much more localized, but they can still be dangerous. Researchers at the 2018 AGU Ocean Science Conference highlighted some of the dangers: "These are unusually fast changes in water level that can catch people off guard and inundate the coast, damage waterfront property, disrupt maritime activities and create strong currents."

They also revealed that meteotsunamis make up 20 per cent of the tsunamis in the world, even though the term is unfamiliar to most; in part because meteotsunamis can masquerade as other phenomena. "For most of the historical record, these waves have been misidentified as either freak waves, tidal waves, or a seiche (as well as mislabeled as rip currents at the shoreline)." Meteotsunami waves occurring on the Great Lakes in particular are often interpreted as seiches -- and to be fair, they have a lot in common (they can even occur at the same time). The main difference between them is that, while the most important driving factor behind a seiche is the wind, a meteotsunami is principally driven by atmospheric pressure. Seiches also generally only occur on enclosed basins while meteotsunami waves are also seen along ocean coasts.

Sources: NOAA | University of Michigan |