- A dangerous natural disaster caused by a set of powerful waves
- Such is its strength, that it can devastate high-rise buildings inland.
The tsunami is one of the most dangerous natural disasters, caused by a group of large waves that can have far-reaching consequences, such as leveling an entire city. Risk is often defined as a combination of the vulnerability of coastal regions and the probability of the event occurring. We explain some facts related to this phenomenon:
What does the word tsunami mean?
Tsunami is a Japanese word used to designate a tidal wave that literally means “wave in the port” or “wave in the bay”, because it occurs in coastal areas. And despite the fact that it has Japanese origin, it is a term that has become very popular around the world to define this great natural disaster.
How is it created?
A tsunami is a set of high-energy ocean waves caused by an underwater earthquake, landslide, or volcanic eruption. A natural phenomenon that when it spreads through the ocean for a long period of time and reaches the coast of a city, it has great destructive power. Such is its strength that it can devastate tall buildings, even inland.
Where is this phenomenon more frequent?
All oceanic regions that are also located in a coastal city can experience the phenomenon. However, it is in the Pacific Ocean and its marginal seas where there is an 80% risk of large tsunamis due to the frequent earthquakes that occur in the Pacific Ring of Fire.
What happens when it hits the shore?
The low point of a tsunami wave crest is the first to reach the shore. When it does, it produces a vacuum effect that sucks the coastal water into the sea, exposing the seabed in its fullness; as if there were low tide. This process is a very important warning signal, since the crest of the wave and its enormous volume usually impact about five minutes later. Recognizing this phenomenon can save many lives.
How fast is it going?
A tsunami can travel across the sea as fast as an airplane: they can cross the entire expanse of the Pacific Ocean in less than a day. The wave travels at a speed of between 500 and 1,000 kilometers per hour, and the higher the speed, the more volume and impact force it will have on the affected areas.
How high can a tsunami wave reach?
In the depth of the ocean, a tsunami is almost impossible to predict on the surface of the sea, since it is a wave that gains strength and height along its path. Although it spawns one meter tall at first, as it approaches the shoreline it can increase in height to over 15 meters.
What damage is it capable of causing?
The damage caused by a tsunami depends on the depth of the sea, the distance to the seabed, the shape of the fault that caused the earthquake, the speed of the great wave in its path and the existing vegetation. Other factors that can influence the degree of devastation is the vulnerability of the populations that are located a few meters from the coast, in areas with low height, weak constructions and lack of a tsunami warning system.
How is a tsunami detected?
Tsunamis are detected by buoys in the oceans and coastal tide gauges that inform scientific establishments in the region. It is here that the minimum changes in sea level are measured and seismic activity is recorded to study the probabilities of a possible tsunami. A tsunami warning goes into effect if a center detects an earthquake of magnitude 7.5 or greater.
What are the areas with the highest risk?
One of the areas with the greatest risk of a tsunami is Japan, as there is a confluence of up to three tectonic plates that move continuously. Reason why it is also a country that has created anti-tsunami barriers and warning systems. Other areas with a high probability of impact are Chile, Indonesia, Hawaii, Cascadia, the Kamchatka Peninsula, Alaska, Oregon and California.
What to do if the city is in danger from a tsunami?
Sensing a tsunami can be the first step in making a decision followed by considering options. Many people use intuition or “rules of thumb” to make decisions that can be helpful: if you get caught in a tsunami wave in the city, it’s best not to swim, but to grab onto a floating object and let the current carry you away.