What is a Tsunami?

DID YOU KNOW that the word Tsunami is from the Japanese language, and it is composed of two seperate words with two seperate meanings...?

In Japanese,'Tsu' means harbour (e.g. like a boat harbour) and 'nami' translates to wave. Together these two words form the meaning of "harbour wave".

Most of you have certainly heard the word Tsunami before, perhaps on the news or mentioned in class at school.

The simplest way to explain a Tsunami is to describe it as a series of water waves which result from the displacement of a huge body of water. Usually occurring offshore in the open ocean, something must cause a lot of water to move in order to set in motion a set of moving wavelengths.

What are the main causes of Tsunamis?

Think for a moment about the sea floor. We know that eventually, how ever deep the ocean may be, there is always a sea bed. Below the bottom of the ocean, far under the thick sand, lies the earth's crust and its many layers. As our planet is one of millions of active stars in the Universe, its inner crusts can move and shift slowly. All of our countries and continents lay above TECTONIC PLATES, which are layers of earth's crust that have shaped our planet as we know it.

Occasionally, these plates will move and cause vibrations and what we know as Earthquakes. Tsunamis most often result from shifting, or converging (e.g. two plates colliding) tectonic plates under the sea bed, which releases a huge amount of energy into the ocean and the overlying water. Once this energy reaches the surface, the sea level rises and the energy spreads out to form the beginning of a Tsunami wave. The energy starts to move, and when it does, these waves can travel many kilometers and reach coastlines.

Are Tsunamis dangerous? In the open ocean, Tsunamis do little damage, as we know the ocean is a HUGE space capable of managing lots of activity! However, now that we know Tsunamis are waves, long and wide, capable of carrying lots of energy, they can also be destructive when they meet shorelines.

When the water is deep, Tsunami waves do not look particularly high, but when they reach shallower areas (e.g.where the sea floor and the surface have less distance apart) they lose energy and gain height. Tsunami waves act like most things; when something carrying energy is forced to a halt (e.g when a wave meets the coastline it is compressed in smaller area) it is forced to release its remaining energy where it can. Unfortunately, when a Tsunami waves hits the coastline, it will release its wave energy and water onto the land. This can be VERY destructive and dangerous for anyone living in these areas. In history, many Tsunamis have taken the lives of entire villages and unsuspecting coastal communities.

RUN! RUN! RUN FOR THE HILLS!      

If a Tsunami were to approach a coastline, the best thing for inhabitants to do is head for high ground. Water will invade lower lying areas, but will need lots of energy to reach higher areas. Therefore, the safest places are far from the shore and higher up!

Nowadays, scientists and researchers are studying Tsunamis very closely, and have developed many warning and prediction systems, able to detect when a Tsunami could form.

"PRESSURE SENSORS" on the sea bed connect to surface buoys which relay information to research centers on land. Instruments like these help humans predict and warm populations of impending Tsunamis.

There are theories that animals may be able to sense approaching Tsunamis, and that can offer clues to us about danger. Elephants have been known to flee into the highlands, and birds have been witnesses flying in large groups above village squawking loudly.

Although Tsunamis have a  very destructive force, they are a fascinating example of the earth's natural power. We should always respect and be cautious of the ocean, and in the event of an earthquake, stay safe, listen for Tsunami warnings, and keep an eye out for the closest hill!