Tsunami: how does this dangerous large wave arise?

We still remember the terrible images after a very heavy earthquake took place near Indonesia near Sumatra. Several countries on the Indian Ocean were battered by that tsunami. This resulted in many deaths, from Thailand to Sri Lanka. What causes this large wave, why does so much energy move through the water and why does it have such serious consequences near the coast?

Tsunami, big wave

  • Where does it start?
  • What do you notice at sea?
  • Tsunami makes landfall and then what?
  • What to do yourself?


Where does it start?

There are several causes that can cause a tsunami. One can be more disastrous than the other. Think of:

  • an underground cavity collapses or part of a mountain slides;
  • an under-ocean earthquake;
  • a meteorite crashes into the sea: the earth has been bombarded by rocks, meteorites and comets since the very beginning and that simply won’t stop. Although the amount of threatening space material decreases with time, there is still a chance that a seriously life-threatening meteorite will one day come this way.

Once a tsunami has been activated, what do you notice at sea and along the coast?

What do you notice at sea?

When one is at sea, no large wave or the like is detected. It may even be that the ripple is so small that it is not noticeable. It is often caused by an earthquake, which sets a large body of water in motion at once. In principle, a water shock wave has been initiated from the center of the circle, with one water particle pushing the adjacent water particle. In this way, energy is transferred to surrounding water. In addition, there is the water that continues as fast as that movement on top of the water, or the relatively small wave. In other words, there is energy transfer at the water depth. And therein lies the danger and not so much the ripple above water level.

Tsunami makes landfall and then what?

The problem of a tsunami becomes apparent when the water-energy transfer comes near the coast. Near the coast the water becomes relatively shallow. This has two consequences:

  • on the one hand, the energy transfer is slower closer to the coast, because the rocks of the coast, as it were, hold back that water force;
  • on the other hand, the water somewhat overtakes itself.

Energy must be dissipated and this can only be done upwards, and the overtaking water can also cause an extra high and extra long-lasting impact. Energy from the sea is therefore removed by bombarding the coast with high-water waves, or the tsunami. Before it comes ashore, a characteristic appearance is the complete retreat of the waterline, as water is drawn in to build the all-dominating wave.

What to do yourself?

We love to travel and so we regularly fly all over the world. The world is divided into many tectonic plates, on which the continents are located. If you come to the coast, this means that there is a chance that it will occur during your visit. Be sure to pay attention to areas that have been affected in recent years. Special measures have been put into effect for this purpose, such as tsunami warning systems and indicated escape routes on site. It is always a good idea to pay attention to this before you enjoy your well-deserved holiday. Knowing your escape route in advance can save your life in the event of unexpected events.

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