A giant wave has left at least 5 dead and 7 injured in a beach restaurant in the province of KwaZulu-Natal, in South Africa. In the video you can see how people are surprised by the spectacle at first, but then panic breaks out, when the water begins to hit several people against the walls at the back of the premises, taking others away again. To the sea.
The rescue forces acted quickly, preventing the number of victims from becoming even greater. It is not the first event of this type that has occurred in the area, so the authorities have already warned the population and tourists so that they do not bathe on the beach. But what is happening? Why are these coastal phenomena occurring?
To answer this question, the first thing we must take into account is that a giant wave It is not the same as a tsunami. At least not necessarily. In general, the origin of tsunamis is very different from that of conventional waves, although these can also cause great damage, as we have seen in South Africa.
Terror in South Africa
The giant wave shook the restaurant on Sunday, September, 17thHowever, there have been more similar events throughout the weekend, in the vicinity of Cape Town.
Some media speak of five fatalities and five others seriously injured. In the absence of official data, what is clear is that the giant wave unleashed panic in the restaurant. But how did it happen?
Some climate experts believe it is due to a spring surge. We must not forget that South Africa is in the southern hemisphere and that they are just a few days away from the start of spring. Some of the climatic phenomena of this season are already wreaking havoc, so the population has been warned to avoid more victims and material damage.
What is the difference between a giant wave and a tsunami?
The main difference between a giant wave and a tsunami is that waves, giant or not, are formed by the wind action, while tsunamis are the result of the movement of ocean plates. Let’s see what all this means.
To begin with, waves do not form simply because the wind moves the water and that’s it. Several factors must converge. First, it generates a pressure change in the air, which sinks the surface of the water a little. This generates a force around it, similar to that generated when we put a toy in a bucket of water and see that it moves. However, in this case there is no object.
When an imbalance occursthe water that sank goes up again, to restore the imbalance. But its vertical speed makes it rise above the initial position. This generates a vertical movement that, now, can be moved by the wind in horizontal direction. We already have the waves. The greater the pressure change, the larger the wave will be, and it will also move more violently the windier it is. There we would have the difference between a giant wave and a smaller one.
A tsunami is different. The crust of our planet is made up of a series of plates in constant movement. This causes their edges to rub or even some to move over or under another. They are movements that little by little generate tensions that can be released suddenly, giving rise to earthquakes.
Now, if these tensions take place in the plates that are under the oceans, the released energy causes a movement of the entire water column. This would be the tsunami. The most normal thing is that it occurs due to earthquakes, although it can also occur due to other violent phenomena that shake the oceanic plates, such as the fall of a meteorite into the sea.
There are big differences between tsunamis and waves, even if they are giant waves. The first thing that stands out the most is the distance between waves. In both cases, they are waves that form in the water, so it will not be an isolated crest, but rather a series of waves that repeat periodically. In the case of waves, the separation between them is approximately 100 meters. On the other hand, with tsunamis, it is hundreds of kilometers.
Another big difference is that waves form above and tsunamis below. That is, the waves are generated on the surface, due to the pressure changes that we have already seen. On the other hand, tsunamis come from the movement of the plates of the Earth’s crust, under water. Therefore, waves affect only a few tens of meters, from the surface downwards, but tsunamis They act on the entire water columnhence its violence.
What is the storm surge occurring in South Africa?
South African authorities and climate experts have explained that the giant wave was the result of a spring surge.
By definition, a storm surge is a tumultuous movement of large waves. This can occur for many reasons. It is very common that they come accompanying storms in which there is a large drop in atmospheric pressure, causing all the phenomenon that we have already seen.
In South Africa, one of these climatic phenomena is now happening with the transition to spring. A great pressure drop that is filling its seas with dangerous giant waves. There is no way around it, so the only thing to do is notify the population, to avoid greater evils like those of the coastal restaurant. The authorities have already done it, now we just have to wait.