Tsunamis are highly destructive natural phenomena because they appear in the form of giant waves that can exceed 30 m in height and can affect large human populations near the coasts or coastal profiles, their most common origin is associated with earthquakes.
Although they are not very frequent events, it is necessary to understand their characteristics, how they are formed, their characteristics, the consequences they generate and the prevention measures to follow.
What is a tsunami?
A tsunami is a sudden natural phenomenon that is generated by the disturbance of offshore waters by some geological event, the most common is usually due to an earthquake, it is characterized by the occurrence of waves that usually exceed 25 meters in height and because They are one of the most destructive natural phenomena.
The tsunami event It consists of the generation of multiple sea waves that approach and end on the mainland in the manner of tides that rise rapidly as powerful currents.
How are they formed?
Most of the normal waves that we see are almost always formed due to winds or tides, however, the tsunamis they have a completely different cause. A tsunami is most often formed by an earthquake, but it can also be formed by an underwater landslide, an onshore volcano eruption, or even a meteorite impact.
Let us remember that even though the tsunamis are associated with giant waves, it is also true that if the event that generated this phenomenon was not very relevant, they will only form microtsunamis, that is, small waves but that can be dangerous for people who do not take preventive measures, these waves will not exceed 3 meters in height.
Important features
- They are sudden events, that is to say that when they occur they can reach coastal populations in a few minutes, so the warning system for towns or cities that may be affected by a tsunami must be efficient and fast.
- They can be generated associated with earthquakes, volcanic eruptions and landslides that occur offshore.
- The waves of a large tsunami can easily exceed 25 meters in height, while those of a microtsunami reach up to 3 meters in height and do not represent much risk.
- About 80% of the tsunamis occur associated with the “Pacific ring of fire” which is the area where there are more earthquakes and volcanism events that also generate tsunamis.
- There are historical records of tsunamis that have been caused by the fall of meteorites into the sea.
- They can reach a speed of 805 km/h similar to jet planes.
- The tsunami waves at the point of origin do not seem to be that big, however as the water approaches the coast these waves grow and slow down.
- When the tsunamis enter land are highly destructive because they carry a large amount of debris in their path and the density of water increases considerably.
- The tsunamis they are different in definition and occurrence than natural tsunamis and sea waves that are generated by wind and tidal events.
Difference between tsunamis and tidal waves
Although both refer to relatively large sea waves with respect to normal ones, the truth is that they are different phenomena and that they have different origins and explanations.
For example, the tidal wave refers to shallow waves caused by the gravitational interaction of the earth, the moon and the sun, in addition, with climatic factors such as storms and strong winds that occur in coastal areas.
Instead, you easily see the difference in that the tsunamis They are formed due to the occurrence of earthquakes, marine volcanic eruptions and marine landslides mainly, which disturb seawater and generate waves.
Causes of a tsunami
Now we have an idea that the tsunamis They are caused or generated by equally unforeseen geological events such as earthquakes, marine volcanic eruptions, landslides or collapses of volcanoes found in the sea and even in the history of the earth have been generated tsunamis due to the fall of meteorites in the ocean.
Tsunamis caused by earthquakes or large earthquakes
It is the most common cause for creating tsunamis in the world, and is directly related to the movement of tectonic plates and subduction zones at convergent plate boundaries.
In this case, a lithospheric plate slides under another plate, generally under the continents in the so-called Pacific ring of fire. When this movement or slide is blocked, energy begins to accumulate until it is released as seismic waves in an earthquake.
It often happens that this release of energy occurs offshore, which causes seismic waves to propagate through the ocean water in the form of waves that become very large when they reach the coast and can reach coastal populations and cause a lot of destruction. in a few minutes.
This type of tsunamis generally they can be predicted and measured, this is because when an earthquake occurs offshore, seismologists carry out studies to find out if this earthquake is a potential generator of a tsunami and in fact there are cities that use warning systems before tsunamis when these events happen
The warning systems tsunamis They are usually activated immediately when the earthquake occurs and people who live nearby must already be in the habit of starting to move away from the coast in case the tsunami occurs.
Tsunamis caused by marine landslides
Just like landslides that occur on the mainland, there are also large landslides and landslides that can occur on the slopes of the seabed, these areas are highly steep and have high sediment content very slip-prone soils, especially and are disturbed. by tremors.
When such an underwater landslide occurs, large masses of sediment, sand, mud, and rock move downslope causing all the surrounding water to be drastically disturbed and can cause a tsunami that can eventually reach the coast and affect coastal towns.
Unlike the tsunamis Caused by earthquakes of this type cannot be predicted since we do not know when the landslide has occurred.
Tsunamis caused by volcanic eruptions
In this case the tsunamis They can occur for a number of reasons, all related to an offshore volcanic eruption.
- A highly explosive volcanic eruption that causes the collapse of the volcanic caldera and a large rock slide that reaches the ocean, that slide generates the tsunami.
- Pyroclastic flows which are a dense mixture of boulders, pumice, ash and gas, eventually in an onshore volcanic eruption can reach the ocean and push the water to cause a tsunami.
This type of tsunamis Theoretically they can be prevented and people who live near those “islands” or close to the volcano can evacuate long before the volcanic eruption, here seismologists are usually monitoring the volcanic and seismic activity before the eruption.
Tsunamis caused by meteorites
In the Cretaceous it is assumed that a large meteorite fell on the surface of the earth specifically close to the coasts of Mexico, that incident due to the great impact of the meteorite and the great speed caused a great tsunami, and at present we must not rule out that at some point it will happen again.
Consequences of a tsunami
The tsunamis They have primary and secondary consequences. The primary consequences are those generated directly related to the passage of the Tsunami at that time. While side effects occur in the minutes, hours, days, and weeks after the event.
The primary effects include erosion and flooding caused in the affected geographical areas.
Flood
The tsunamis They are events that can cause a drastic change in the environmental conditions of the affected geographical area, for example, they can completely flood an area with seawater and destroy all the fauna and flora that existed.
This effect also makes the soil unusable for a long time.
Erosion
Due to the power with which the sea waves hit the coast, the speed of the water and its density, a highly visible erosive effect is generated, that is, the water drags all the sediments from the ground, breaks the rocks in its path and it also destroys all human constructions.
This effect causes the landscape of the area to change drastically.
Fires
This effect is one of the most dangerous because a tsunami, apart from its destructive power that can damage human constructions in its path, leaves a large amount of debris, wires, solid waste and scattered fuels, which can easily react and create fires. that aggravate the situation.
Contaminated drinking water
The coastal areas are often supplied with fresh water by exploiting the water with wells, in addition, it is common for the water to be stored in large tanks and pools very close to the coast and towns on the coast.
When the tsunami occurs, it is common for these water wells, swimming pools and places where fresh water was stored to be contaminated with salt water and debris carried by the tsunami.
In addition to that they can effectively destroy all water supplies to the town.
Outbreaks of infections and diseases
It is common that after this catastrophic event occurs, several people have been affected and injured, in addition to the environment being left full of garbage and debris that results in the accumulation of rodents, mosquitoes and other animals that can cause diseases, infections and infections.
Building collapse
The tsunamis They are events that cannot be stopped even with the strongest wall in the world, although it has been tried. Any construction made by the human being currently succumbs to this natural phenomenon without exception.
How to prevent a tsunami?
Due to the way in which the tsunamis They cannot be prevented or predicted exactly when they will occur, however, if an efficient system can be created to avoid human losses, unfortunately preventing the construction of houses, buildings or any construction from being lost is not possible, due to that a tsunami is considered totally destructive in its path.
Populations that are prone to this natural phenomenon can avoid disasters if they create an alarm system that notifies when there is a possibility of a tsunami occurring.
As we already know these generally occur due to offshore earthquakes, so when the earthquake occurs and is over, people near the coast should start an orderly evacuation to higher areas that can be called “safe zones”.
Let’s summarize the procedure:
- First, an alert system must be created to identify the possibility of a tsunami occurring, these systems can be general alarms in the town or city, mobile applications and the news in the area.
- Constant drills must be carried out based on the alarm system against tsunamis to identify safe areas and evacuation routes to higher parts in the area that may be affected by the tsunami.
- Children should be taught from school how to act in the face of these natural events.