Rissaga or Meteotsunami: What is it, how it is formed and why it is dangerous

A Rissaga is a meteorological and oceanographic phenomenon that causes rapid and significant oscillations at sea levelsimilar to those of a tsunami, but caused by changes in atmospheric pressure instead of seismic activity. This phenomenon can cause rough up and down of water in a short period of timewhich can result in sudden floods and damage to the affected coastal areas.

They usually occur in specific regions where geographical and atmospheric conditions favor their formation. For example, in the Mediterranean Sea, especially in the Menorca IslandRissagas are relatively common. In these areas, a combination of rapid changes in atmospheric pressure, strong winds and private marine topography can trigger these oscillations.

1. The beginning of a Meteotsunami is linked to a disturbance in the atmospherelike a storm, a turbonada line, a meteorological front or an atmospheric wave of gravity. These events cause rapid changes in atmospheric pressure and generate strong winds.
2. Abrupt changes in atmospheric pressure and strong winds create waves on the sea surface. These waves can be similar to the waves produced by a moving ship, but on a much larger scale. It is necessary that the speed of atmospheric disturbance coincides with the speed of sea waves so that a resonance occurs, thus amplifying the waves.
3. The waves generated in the sea spread to the coast. The topography of the seabed and the shape of the coast play an important role at this stage. In areas with wide continental platforms and narrow bays, waves can concentrate and amplify as they approach the earth.
4. When the waves reach the coast, interact with the shape of the coast and the characteristics of the seabed. In bays or ports with certain geometric characteristics, waves can increase significantly in height due to resonance and topographic amplification effects.
5. The final result is a series of rapid and pronounced oscillations at sea level. These oscillations can cause water to rise and fall several meters in minutes. This behavior is similar to that of a tsunami, but with an atmospheric origin instead of seismic.

Rissagas, or meteotsunamis, although they are less known than conventional tsunamis generated by earthquakes, can represent serious dangers for the affected coastal areas:

• Sudden floods: This phenomenon can cause rapid and significant rises and drops from sea level, causing sudden floods in coastal areas. This type of flood can occur in a matter of minutes, leaving little time for evacuation and preparation. Infrastructure close to water, such as ports, marine and coastal establishments, are particularly vulnerable.
• Infrastructure damage: The strength and speed with which water moves during a rissaga can cause serious damage to coastal infrastructure. Springs, boats, roads and buildings near the sea can be destroyed or severely damaged. Mooring ships can break their moorings and be dragged, colliding with other vessels or with the coast.
• Risk for human life: Rissagas represent a significant danger to human life, especially for those who are close to water or small vessels.
• Economic Impact: Rissagas can have a considerable economic impact on coastal communities. Damage to infrastructure and vessels, as well as interruptions in economic activities, such as fishing and tourism, can result in significant economic losses.

This phenomenon can occur in various parts of the world, especially in regions where atmospheric and geographical conditions are conducive to their formation. However, one of the best known places and studied by the frequency and magnitude of these phenomena is the archipelago of the Balearic Islandsparticularly in the Menorca Island.

Rissagas in the Balearic Islands are usually associated with rapid changes in atmospheric pressure. These variations can be caused by storm systems, cold fronts and other meteorological phenomena that cross the Mediterranean. The presence of these atmospheric systems generates waves on the surface of the sea that can become meteotsunamis.

The particular geography of the coast of Menorca is crucial for the formation and amplification of Rissagas. The Ciutadella Bayin the west of Menorca, it is especially prone to these phenomena due to its narrow and elongated form. This geographical configuration allows sea waves to concentrate and amplify as they approach the coast, increasing the height of sea level oscillations.

Given the frequency and severity of the rissagas in Menorca, several measures have been implemented to mitigate their effects:

• Early alert systems: Monitoring and prediction systems have been improved to provide early alerts to coastal communities.
• Resilient infrastructure: The construction and adaptation of coastal infrastructure to resist rapid oscillations from sea level.
• Education and preparation: Education and preparation programs for the local population and tourists, in order to improve the response to these events.

In addition to the Balearic Islands, other Mediterranean regions also experience Rissagas, although less frequently and intensity. Some of these areas include:

• Aegean Sea Islands: The Greek islands in the Aegean Sea, due to their geography and atmospheric conditions, can also experience meteotsunamis.
• Italy coasts: particularly in the Adriatic region, where coastal topography can favor the amplification of sea waves.

Although less frequent, Rissagas are also registered in other parts of the world. Some examples include:

• Japan: The west coast of Japan has experienced meteotsunamis due to rapid variations in atmospheric pressure.
• USA: In the Gulf of Mexico and the east coast of the United States, Meteotsunamis linked to strong storms and weather systems have been reported.

Now that you know what rissagas or meteotsunamis are, you may also be interested in reading these articles on what is the largest tsunami in the world and what is a tidal: definition and its characteristics.

If you want to read more articles similar to Rissaga or Meteotsunami: What is it, how it is formed and why it is dangerouswe recommend that you enter our category of meteorological phenomena.