A meteo-tsunami (meteorological tsunami) is a rare natural phenomenon in which a large and sudden displacement of water occurs, often caused by atmospheric pressure changes rather than seismic activity (as in a regular tsunami). Although meteo-tsunamis are less powerful than seismic tsunamis, they can still cause significant damage to coastal areas.
How does a meteo-tsunami form?
Meteo-tsunamis occur when a rapid atmospheric disturbance—such as a thunderstorm complex, a sudden wind gust, or an air pressure wave—transfers energy to the water surface and generates a wave that behaves like a tsunami. In short, a meteo-tsunami is a wave that forms under rare meteorological conditions rather than due to seismic activity, as is the case with regular tsunamis.
What triggers a meteo-tsunami and how can it grow?
In most cases, meteo-tsunamis are triggered by rapid air pressure changes. When the air pressure suddenly drops, there is temporarily less mass pressing down on the water, causing the water surface to rise (see Figure 1). A wave forms and gradually starts moving, often traveling along with the sharp pressure change. When the wave reaches shallow water, it slows down, and its height increases. Eventually, the wave breaks on shore or in harbors, where it can cause damage.
Figure 1: A sudden drop in air pressure reduces the weight on the water, causing its surface to rise.
If the speed of the atmospheric disturbance matches the speed of the wave it generates, the wave can amplify, similar to how a child on a swing, swings higher by receiving a push at the right moment.
Additionally, other forms of resonance can further strengthen the wave. One example is harbor resonance— when the incoming wave becomes trapped in a bay or harbor, it can be amplified through reflection. Another phenomenon is shelf resonance —when a wave follows the contours of a continental shelf (or seabed), it can grow in size due to the right interaction with the ocean floor.
Historic meteo-tsunamis and their impact
Menorca, Spain – June 15, 2006 & July 16, 2018:
A sudden pressure change over the Mediterranean Sea, caused by a storm, led to waves over 4 meters high in the harbor of Ciutadella (Menorca). The speed of the pressure wave matched the speed of the ocean waves, amplifying the wave. Additionally, harbor resonance may have further contributed to the wave’s intensification. Yachts and fishing boats were swept over the docks and damaged, and the harbor’s quays were also flooded.
Nagasaki, Japan – March 31, 1979:
A sudden air pressure increase of 3 hPa within a few minutes generated a meteo-tsunami that reached the Japanese coast. The wave ultimately reached a maximum height of 5 meters, aided by the geography of the bay surrounding Nagasaki. Here too, the meteo-tsunami caused damage to the harbor, boats, and docks. No fatalities were reported.
Daytona Beach, Florida, VS – July 3, 1992:
A squall line, a line of severe thunderstorms, moved across the Daytona area, causing a significant pressure change within just a few minutes. A meteo-tsunami formed and was likely amplified by Florida’s shallow coastline. Eventually, waves of approximately 3 meters high flooded the beaches along Florida’s east coast.
Vela Luka, Croatia – June 21, 1978
A strong storm over Italy caused a rapid pressure drop over the Adriatic Sea. A meteo-tsunami formed and was significantly amplified by the shape of the Adriatic Sea (resonance effect). Eventually, waves up to 6 meters high caused severe damage to harbors and buildings along the Croatian coast.
These examples show that meteo-tsunamis are very rare. Moreover, their impact on the environment is often very localized, unlike a seismically generated tsunami.
(Un)predictability
Meteo-tsunamis are difficult to predict. They occur only very rarely under highly specific conditions. Current weather models are not yet capable of indicating the formation of a meteo-tsunami. Since meteo-tsunamis do not have a geological cause, standard tsunami warning systems usually do not detect them. However, the expertise of a meteorologist can help assess the likelihood of a meteo-tsunami. If all the necessary ingredients for a meteo-tsunami come together, our meteorologists can warn our clients accordingly.
Impact on offshore operations
The impact on offshore operations is small. A potential meteo-tsunami only becomes dangerous once the wave reaches shallow water. For nearshore operations, however, it is a completely different story. There, a meteo-tsunami can cause serious damage to equipment and people. Fortunately, a meteo-tsunami is a very rare occurrence.
If you have ever experienced a meteo-tsunami yourself, let us know! We are curious to hear your story about this fascinating weather phenomenon.
