Seiches and meteotsunamis. What’s the difference?
Seiches and meteotsunamis are often grouped together, but they are two different events. Winds and atmospheric pressure can contribute to the formation of both seiches and meteotsunamis; however, winds are typically more important to a seiche motion, while pressure often plays a substantial role in meteotsunami formation. Sometimes a seiche and a meteotsunami can even occur at the same time. Seiches are standing waves with longer periods of water-level oscillations (typically exceeding periods of three or more hours), whereas meteotsunamis are progressive waves limited to the tsunami frequency band of wave periods (two minutes to two hours). Seiches are usually limited to partially or fully enclosed basins, such as Lake Erie. Meteotsunamis can occur in such basins but are also prevalent on the open coast. A single meteotsunami can travel long distances and influence a very large range of the coastline.
You’ve heard of tsunamis—those giant oceanic waves triggered primarily by earthquakes that can roll ashore, causing loss of life and disaster. But have you heard of meteotsunamis?
Meteotsunamis are large waves that scientists are just beginning to better understand. Unlike tsunamis triggered by seismic activity, meteotsunamis are driven by air-pressure disturbances often associated with fast-moving weather events, such as severe thunderstorms, squalls, and other storm fronts. The storm generates a wave that moves towards the shore, and is amplified by a shallow continental shelf and inlet, bay, or other coastal feature.
Meteotsunamis have been observed to reach heights of 6 feet or more. They occur in many places around the world, including the Great Lakes, Gulf of Mexico, Atlantic Coast, and the Mediterranean and Adriatic Seas.
Identifying a meteotsunami is a challenge because its characteristics are almost indistinguishable from a seismic tsunami. It can also be confused with wind-driven storm surge or a seiche. These uncertainties make it difficult to predict a meteotsunami and warn the public of a potential event. However, NOAA scientists have identified atmospheric conditions that are likely to generate a meteotsunami and continue to work on ways to forecast them.