Understanding tsunamis: how these devastating phenomena occur ?

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The study of tsunamis has its roots in the depths of history, well before the modern era. Ancient civilizations already recorded these terrifying events in their stories, just as they did with volcanoes. The Greeks, for example, mentioned gigantic waves in their writings; the tsunami caused by the eruption of the Thera volcano (Santorini) around 1600 BC, is often cited as one of the first such events to be recorded.

Japan, also repeatedly hit by these devastating waves, has a long history of stories relating these disasters; which explains the origin of the term “tsunami” himself. The term tsu nami in Japanese literally translates to “harbor wave”. Over the centuries, observations and descriptions of tsunamis have accumulated and allowed humans to begin to unravel the mysteries of these phenomena.

However, we had to wait scientific and technological progress of the 20th century so that in-depth studies of tsunamis can be conducted. The advent of oceanography, seismology and other disciplines has allowed researchers to collect precise data and analyze the mechanisms underlying the formation and to the propagation of tsunamis.

Real global awareness of this phenomenon was heightened by the terrible tsunami of 2004 in the Indian Ocean, taking with it more than 230’ nbsp;000 people. It is still considered today as “ the worst global catastrophe of the 21st century ” according to this article published on Oxford Academic by James Goff and Walter Dudley. More recently, the Tōhoku tsunami that struck Japan in 2011, killing 16,0000 people, also caused a serious crisis at the Fukushima Daiichi nuclear power plant. These tragic events opened the eyes of the world to the existence of these phenomena and highlighted the urgent need to better understand them.

A born scourge of the depths

Tsunamis are one of the natural phenomena the most formidable and devastating that our planet can face. This tidal wave of geological origin originates mainly following an underwater or coastal earthquake of magnitude greater than 7.5. These often occur at shallow depths and are generally located at subduction zones, where two tectonic plates meet and one dips beneath the other. These “ are also characterized by numerous seismological, tectonic and magmatic manifestations ” explains to us Futura Sciences.

A tsunami can also occur following an underwater volcanic eruption or a landslide. In any case, these events, by suddenly displacing a large mass of water, give rise to immense waves which travel at staggering speeds which can sometimes reach 800 km /h over several hundred kilometers on the surface of the ocean. The video below from Trial Exhibits, Inc, although quite old, does a good job of showing how a tsunami forms.

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If these waves are so devastating, it is because they manage to concentrate colossal energy in immense volumes of water. As they approach the coast, these waves see their speed decrease while their height increases dramatically, reaching up to several hundred meters. In the case of the 1958 Lituya Bay megatsunami, some researchers estimated that the wave reached a height of 525 m! Downright terrifying. The excellent YouTube channel RED SIDE published a video three years ago (see below) where we can see the monstrous nature of these waves by comparing their sizes to objects.

It is during this phase that the tsunami becomes particularly destructive, hitting the coastlines with incredible force and causing devastating floods. The height and power of the waves are such that they can devastate everything in their path, leaving behind devastated landscapes and completely traumatized populations.

The consequences of tsunamis are often dramatic, affecting human lives and destroying infrastructure. Entire villages can be wiped off the map in minutes, and the economic damage sometimes amounts to billions of dollars. This is why understanding tsunamis and setting up early warning systems are crucial issues to improve the protection of coastal populations.

How to protect yourself from these monsters ?

As it is impossible to accurately predict the occurrence of’ #8217;such a phenomenon, the prevention of tsunamis and the minimization of their impacts constitute essential issues. The effectiveness of these measures relies largely on the ability to detect tsunamis as soon as they form and to quickly communicate alerts to the populations concerned.

Since 1965, tsunami warning systems have been set up internationally, forming a complex network of seismic stations and buoys in sea. This network of ocean sentinels constantly monitors earthquakes likely to generate tsunamis and variations in sea level which signal the approach of a colossal wave. When an earthquake of significant magnitude occurs underwater, it is immediately evaluated to determine its triggering potential. a tsunami.

If so, data centers quickly analyze the information and issue alerts to state and local authorities. These then relay the alert to the population via sirens, text messages and other means of mass communication, allowing everyone to take the necessary measures to protect themselves. make safe.

Beyond warning systems, urban planning and the construction of infrastructure resistant to these deadly waves is also part of the risk management protocol. In some regions, such as Japan and certain American states such as Alaska and Hawaii, significant investments have been injected for years. These have enabled the construction of protective walls, dikes or other physical barriers capable of reducing the impact of waves on inhabited areas.

At the same time, the authorities of the countries affected by the risk are developing evacuation plans and organizing regular exercises with the population to ensure that it reacts to protect itself as best as possible. These exercises make it possible to test evacuation procedures and familiarize residents with emergency routes. Any measure is good to take, but tsunamis are proof that we are nothing compared to Mother Nature and that she will always have the last word on our civilization, however technological it may be. elle.

• Tsunamis, triggered by underwater earthquakes or other similar geological phenomena, propagate immense waves at high speed across the oceans.
• Tsunamis ;#8217;modern alerts, established since 1965, use seismic and oceanographic data to quickly warn coastal populations of a possible tsunami threat.
• Current prevention measures include protective infrastructure and regular evacuation drills to minimize human and material damage.

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