What Are Meteotsunamis? (Credit: NOAA National Ocean Service)

While the term meteotsunami might sound like the name of the latest natural disaster science fiction thriller, it is actually the name of a very real phenomenon that can occur in various bodies of water around the world.  To put it simply, a meteotsunami is similar to a tsunami, however, instead of being caused by seismic activity they are caused by rapid changes in barometric pressure that cause water displacement.     
The rapid change in air pressure needed to trigger a meteotsunami can be associated with fast moving weather phenomena such as severe thunderstorms or squalls moving over a body of water.  As these storms move over a body of water, the rapid change in pressure causes a wave that moves towards the shore and becomes more amplified by a shallow continental shelf as well as by coastal features such as bays or inlets.  These storms usually interact with the body of water for a short period of time, which could be anywhere from a few minutes to a few hours, and have been observed to reach heights of 6 feet or higher. The features of meteotsunamis are almost indistinguishable from that of a typical tsunami.  The main way of differentiating between the two is looking for the presence of seismic activity during the occurrence of a tsunami-like event. If a tsunami-like event has occurred when there was no recorded seismic activity but a fast moving weather system such as a squall line had moved over the body of water near the area, it is likely that a meteotsunami, not a tsunami, had occurred.     
Another meteorological phenomenon that meteotsunamis are often confused with are called seiches.  Seiches are wind-driven standing waves with long periods of water-level oscillation. While they can be caused by the same types of weather events as meteotsunamis, and can often occur at the same time, seiches are primarily caused by the wind rather than pressure changes. Additionally, while seiches are standing oscillations of water level over a period of three or more hours, meteotsunamis are progressive waves that fall under shorter wave oscillation periods ranging from two minutes to two hours.

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©2019 Meteorologist Stephanie Edwards