What is a meteotsunami

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Un Meteotsunami It is a meteorological phenomenon that consists of a series of damaging ocean waves that have the same temporal and spatial scales as an ordinary tsunami, but with several differences. While ordinary tsunamis are seismic in origin, meteorological tsunamis are not, that is, they are not caused by underwater earthquakes, oceanic landslide, or the influence of meteorites in the sea.

In this article we are going to tell you what a meteotsunami is, what its characteristics are and its consequences.

What is a meteotsunami

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Meteotsunamis are caused by rapid changes in atmospheric pressure, such as cold fronts from severe thunderstorms or squall lines, which are combined with the speed, mass and intensity of the waves.

The combination of these events produces a wave that is concentrated as it reaches land, but its incidence on the coast depends on the characteristics of the continental shelf. Shallow bay depths or long narrow ports provide the most enhanced resonance and are therefore affected the most.

The difference between meteorological tsunamis and storm surges is that they are difficult to predict. These can disappear producing moderate waves or flooding coastal areas with large volumes of water.

In the Spanish Mediterranean islands, meteotsunamis are called rissaga. In mainland Spain they are rissagues, marubbio in Sicily, abiki in Japan and seebär in the Baltic.

The strongest recorded meteotsunamis

what is a meteotsunami

The strongest meteotsunami to date occurred in Croatia on June 21, 1978. Hit the coast of Vela Luka on the island of Korčula with 60-meter waves. The waves came and went for several hours, starting at 5:30 in the morning. He invaded the port and entered the city about 650 meters from the coast, laying waste to everything in his path. However, the phenomenon is not only local, but affects large areas in the south-central Adriatic, between Croatia and Montenegro, and between Giulianova and Bari in Italy.

In 2008, a meteotsunami up to 36 meters high hit the port of Boothbay, Maine, USA. In 1929, a larger meteorological tsunami hit Lake Michigan, killing ten people from the waves. In 1979, Nagasaki Bay was damaged by abiki, and in 1984 waves of up to 4 meters occurred in the Balearic Islands. Other meteotsunamis they were observed off the coast of Chicago in 1954, in Pune in 2009, and in the Chesapeake Bay on the east coast of the United States in 2012.

Rissagas in Europe

As expected, this phenomenon is very strange, and attempts are being made to find the cause of its origin. This phenomenon has been known for a long time, especially in Ciutadella. There are some references to shipwrecks in the port of Ciutadella in the fifteenth century. It is all these tides that have extraordinary magnitudes and occur in a short period of time.

The usual thing is that the magnitude of astronomical tides taking into account the Mediterranean Sea is usually around 20 centimeters in a few hours. This is something that is almost invisible to the naked eye. Nevertheless, the rissagas produced amplitudes of more than 2 meters in length in just 10 minutes.

The origins of the rissagas were not known until recently, when more was known about the weather and the role of the tides. It is thought that the origin of the rissagas may be astronomical. This means that it has a type of operation similar to that of the tides. It is also thought that it may have a seismic origin. This can occur due to various waves produced by submarine earthquakes, which are amplified when they reach the port. However, all these assumptions are sufficient to explain the phenomenon. At least the explanation is that this phenomenon was very frequent in this particular orchard and not in other orchards.

The real cause was not known until 1934, after several studies of unusual fluctuations in sea level. Research suggests that the cause of the rissagas is the atmosphere. Sudden large fluctuations in sea level are associated with other sudden fluctuations in atmospheric pressure. Take Ciutadella in the Balearic Islands, which is the result of the interaction of the atmosphere and the ocean. Some authors believe that rissaga is a theory that arises from the effects of gravitational waves produced in the middle troposphere. These gravitational waves occur because wind shear is caused by oscillations in atmospheric pressure at surface level.

Atmospheric condition of a meteotsunami

Meteotsunami

There are a variety of atmospheric conditions that are most likely to promote meteotsunami. The 3 main atmospheric conditions that favor this phenomenon are the following:

  • There should be strong southwesterly winds in the middle and upper troposphere. These winds must blow before affecting the deep valleys of the Iberian Peninsula.
  • For water levels below 1500 meters, there must be a high-quality air mass that results in a strong temperature inversion between the water level and the air above the sea surface. Surface air will be cooler than this.
  • The surface should have weak to moderate easterly currents.

The last condition, if it has been recently verified, it is not entirely necessary for rissagas to occur. Rissagas from southerly or south-westerly winds can sometimes be observed on the surface. Experts in Mediterranean meteorology have concluded that these favorable atmospheric conditions for rissagas occur during the warmer half of the year. Therefore, the maximum frequency of this phenomenon occurs between April and October.

Associated times

One of the fundamental aspects that must be considered for the prediction and monitoring of rissagas is the climate that characterizes these conditions. On days when rissagas occur, the sky is often covered by layers of dense, opaque high clouds. As usual, It is rarely cloudy below, but the sky is characterized as overcast and yellow due to haze. Smog emerges from dust blown in from the African continent. In other cases, just a few scattered clouds do not indicate significant vertical motion.

I hope that with this information you can learn more about what a meteotsunami is and its characteristics.


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