What is a Tsunami?

 What are Tsunamis?

On Boxing Day 2004 a horrific wave swept across the Indian Ocean killing over two hundred and thirty thousand people. After receiving massive media coverage, the topic of Tsunamis became widely discussed for a time before dying down. However, this topic of discussion returned abruptly in March 2011 when a Tsunami devastated the Japanese East Coast. But what are Tsunamis? What causes them?

Contrary to popular belief, a tsunami is not a single wave, but rather a series of large waves. It’s not so much the amplitude of a single wave which does the damage, but the accumulated power and volume of water brought about by a series of waves. Tsunamis often have little resemblance to a normal wave due to the much larger wavelength, which causes them to sometimes appear as a rapidly rising tide, hence why they are sometimes called tidal waves.

Tsunamis are caused when a large volume of water is displaced, which most typically occurs in the ocean as a result of seismic activity, such as subduction – the process by which an oceanic plate is forced beneath a continental plate . Theoretically any number of scenarios could result in a tsunami such as meteorite impacts, landslides, and nuclear detonation. Anything that has the potential to quickly displace large volumes of water has the potential to cause a tsunami.

Tsunamis are a large hazard to human populations because, although damage is restricted to coastal areas, they waves spread in a circular pattern away from the source and can therefore devastate entire ocean basins, as was seen with the 2004 Indian Ocean Tsunami. Damage caused by tsunamis can be economic or social, the Indian Ocean tsunami killed thousands of people, but it also had a huge impact on the tourist industry, which is only now beginning to recover.  We need only look to Fukishima in Japan to see other indirect impacts, where damage to a nuclear power station is having serious complications.