A Magnitude earthquake 8.8 that, according to experts, it could be the largest registered sixth, hit the northern Pacific In front of Russia at dawn on Wednesday, which caused Tsunami alerts and evacuations in Hawaii, Alaska, California and Japan, and left millions of people anxiously waiting anxiously waves that, according to meteorologists, could reach 3 meters in some places. In fact, in Japan there are already people AGOLPADA on the roofs.
A good idea, at first.
Causes and natures. Tsunamis are phenomena of great destructive power that, in most cases, originates after An underwater earthquakewhen an abrupt movement of tectonic plates displaces huge volumes of water and generates waves that spread in all directions such as waves in a pond.
Although not all coastal earthquakes produce tsunamis, those that manage to be generated may have devastating consequences in nearby areas and, sometimes, sometimes travel thousands of kilometers At the speed of a commercial plane, wreaking havoc in places far from the epicenter, as it is. All these guidelines are occurring after The earthquake in Russia.
Coming. In an open sea they can go unnoticed for a ship, but when approaching the coast, the waves increase its height and acquire destructive potential. In addition to earthquakes, tsunamis can be triggered by volcanic eruptions or, more rarely, due to weather alterations that modify atmospheric pressure, giving rise to the so -called meteotsunamis, such as the one in 1954 mortally surprised to bathers In Lake Michigan.
Early forecast and detection. Although earthquakes They cannot be predictedimmediate monitoring after its occurrence allows to assess whether there is a risk of tsunami. For this, a global network of underwater sensors is used that detect minimal pressure variations, together with computer models capable of projecting the possible route and strength of the waves.
In this way, governments and alert centers activate emergency systems that include sirens, radio, television or official applications. Approximately 80% of tsunamis They are generated in the Pacific Ocean, particularly in the call Fire beltwhile the Atlantic and the Caribbean represent just 10%. In the United States, although rare, the west coast is the most vulnerable: History records mortal episodes as The 1946 tsunamicaused by an earthquake in the Aleutian Islands, which ended the lives of five people in Alaska and about 160 in Hawaii.
Preventive preparation and measures. The International organizations insist on the importance of Citizen preparation. The main thing: It is recommended to know the community evacuation plans and practice the planned routes, as well as identify the flood areas by tsunamis in each locality.
It is also advisable to have multiple ways To receive emergency alerts, either through NOAA radios, official applications or local warning systems. In words of specialistseach person must “know their threat”, that is, be aware of whether their place of residence is within a risk area.
How to act before an imminent alert. Thus we reach the current situation. If an earthquake occurs, the first thing is shock: bend down, cover under a solid table or object and stay in position until the movement ceases. Then, if there is a risk of tsunami, the instructions of the authorities must be obeyed and moved as quickly as possible to High and remote areas of the sea.
However, experience shows that waiting for an official notice It can be lethalrecognizing natural signals can save lives. Namely: a tremor so strong that prevents standing, a rumble from the ocean or a sudden and unusual decline in water on the coast. It should be remembered that not all tsunamis begin with that setback: on many occasions, the first wave that arrives is directly the crestwithout prior notice. In such circumstances, the only safe option is the immediate self -evacuationsince even a couple of minutes of delay can make the difference between life and death.
And get on a roof? The images that are being making viral With gutting people on roofs close to the coast it is a resource that can save lives in certain circumstances, but it is not the ideal option and should be understood very carefully. The main agencies Emergency management (such as NOAA, the Pacific tsunamis alert, JMA or UNESCO/COI) agree that the priority recommendation is always evacuated towards Earlier Land and as far from the possible sea.
However, the same agencies recognize that when time is extremely limited or there are no safe routes available, looking for height In solid structures It can be the only viable alternative.
The Japanese case. Obviously, in the case of Japan, a country with a long history of tsunamis and a high degree of preparation, many coastal cities They have built what they call “vertical evacuation structures”: reinforced concrete buildings or towers specifically designed for Resist the impact of waves of great magnitude.
In fact, the JMA and local governments instruct the population to, if it is not possible An accepted strategy. After the devastating Tsunami of 2011which swept a large part of the Tōhoku region, the construction of these intensified Vertical shelters and the signaling that indicates which buildings comply with the standards to support waves up to several meters high.
The “but.” The problem is that not all roofs are safe. For example, getting into a small building, poorly built or close to the coast can be even more dangerous: water can exceed the structure, weaken its foundations or drag it.
Studies of the National Tsunami Hazard Mitigation Program In the United States and UNESCO (in their guidelines) they point out that only the buildings designed or evaluated for this purpose must be considered shelters. In areas where there are no certified constructions, the safest option remains the same: move horizontally to high ground.
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