March 22nd – 28th marks international Tsunami Awareness week. In the past decade humanity have witnessed to devastating tsunamis; Boxing day 2004 and Sendi March 11th 2011, both giving the world the bleak reminder of waters destructive power. But what actually is a tsunami and why are they so destructive?
a long, high sea wave caused by an earthquake or other disturbance.
The literal translation of ‘tsunami’ is ‘Harbour Wave’. This comes from the fact in open water a series of tsunami can travel thousands of mile visibly undetectable until they reach shallower waters causing them to rise up to the walls of water we know them to be.
They are caused by a large displacement of water most commonly by an earthquake or landslide, and are by far one of the most deadliest types of natural disaster. If you are in a coastal area and feel an earthquake it is often best to head to higher ground even if a tsunami alert has not been given, although most areas prone to tsunamis have quiet good warning systems waves still travel at speeds of up 500 km per hour, so even a few minutes warning may not always be sufficient.
The first warning of an income tsunami is often what is known as draw back. As water is displaced is often pulls water out to sea, so if you were sat on the beach it would appear as if the sea was withdrawing like at low tide but very quickly. Again if you see this, always best to get to high ground as quickly and calmly as possible.
A common misconception is that a tsunami is one wave, it is actually a series of waves. Also the first is often not the most powerful. This is why it can seem as the water just keeps coming as it gets further inland, its being forced by further waves.
Subduction zone earthquakes tend to cause the most powerful and deadly tsunamis such as the Boxing day or Sendi however the largest ever wave ever recorded was from a landslide induced tsunami at Lituya Bay, Alaska in 1958. Waves reached over 500 meters tall all this is in part the the shape of the bay as opposed to a landslide going in to open waters. Over 80% of tsunamis occur in the Pacific Ocean, the ring of fire.
If you are on a coast line in a at risk area, especially if holidaying and not too familiar with the area, make sure you check for evacuation routes and either easy access to high ground or strong, stable buildings which you can take shelter on high floors (wooden or unstable structures can be washed away!).
If you would like to know more here is a list of Tsunami Awareness Week links;