How Tsunamis Work

2004 Tsunami

tsunami 2004In 2004, man was once again brought down to its knees by the devastating power of mother nature. And this time that reminder did not come from the skies or from the land, it came by sea.

On December 26, 2004, an undersea earthquake with a measure of 9.3 magnitude occurred off the western coast of Sumatra, Indonesia. With that magnitude, the earthquake quickly gained prominence as being the second largest earthquake in history. But the most terrifying event was not the earthquake itself but what followed.

The strong earthquake created several massive tsunamis that devastated the shores of communities along the Indian Ocean including parts of Indonesia, Sri Lanka, India, and Thailand. With a death toll of more or less 300,000, this tsunami is considered the deadliest one yet in recorded history.

What is a tsunami?

The etymology of the word “tsunami" has Japanese origins. The word is formed by combining two Japanese words, “tsu” which means harbor and “nami” which refers to waves. So literally, a tsunami is a huge wave or a series of huge waves.

Tsunami waves has been known to be as tall as 34 feet or 10.5 meters and can stretch to a couple of miles long. But don’t let their height and length fool you. These waves are fast, really fast. The waves can travel up to 500 to 600 mph or 800 to 1000 kph.

The birth of a Tsunami

Tsunamis are commonly caused by undersea earthquakes. When movements in the tectonic plates on the Earth’s surface occur, earthquakes and volcanic activities become evident. The earthquakes and volcanism are two possible sources of tsunamis.

The movements of the plates releases enormous force which is transferred to the water. The force from the sea floor pushes the water upwards creating those massive waves. Although underwater earthquakes and volcanism are the more common causes of tsunamis, there are two other natural occurrences that can create the devastating waves.

These are submarine landslides and submarines volcanoes, both are most likely accompanied with earthquakes which adds to the overall force that displaces the water in the seas.

Also, a huge meteor or asteroid-collision events can exert enough force to create very huge tsunamis. It has been theorized that such an event might have caused giant tsunamis that changed the Earth’s landscape billions of years ago.

After the seismic activities on the sea floor pushes the sea upward, the Earth’s gravity forces the water to go horizontally along the surface. The energy pushes the water away from the source, towards the direction of land, pretty much like the ordinary waves.


Tsunamis travel fast. Never attempt to outrun because you won’t be able to make it. A tsunami wave moves quicker in deeper water than in shallower water. When if moves in deeper waters, it is hardy noticeable but will become more evident as it approaches the shore lines.

The energy of the tsunami waves is being compressed by the water and the coast which causes the tall devastating waves. If you’re seeing the waves, you’re already too close.

The most serious problem facing humans is the fact that tsunami waves, once in motion, cannot be stopped. Scientists and civil agencies can only devote resources to predicting tsunamis and creating effective plans for protecting coastal areas from their ravages.

Image Source: Wikipedia

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