The Sprout

Japan Earthquake: An Explanation

Posted by Sambow from Cardiff - Published on 14/03/2011 at 11:05
4 comments » - Tagged as Climate, Environment, History, People, Topical

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I’m sure by now a lot of you are aware of what has happened in Japan. You probably all know what catastrophic effects the earthquake there had. We hear about earthquakes and such on the news, more often than not concerning Japan, but why do they happen?

It’s quite hard to understand current affairs when the dynamics of them are so unclear.

So I’ll try my best here to try and explain, for those of you don’t know, how these earthquakes keep happening in Japan and why they sometimes have such negative and cataclysmic effects.

The world is split up into eight main tectonic plates, continental and oceanic. Japan has the unfortunate job of being located on a three split boundary of the Eurasian, Pacific and Philippine plate. Why is that bad? Because plates are always moving due to convection currents underneath the Earth’s surface, sometimes they move away from each other and sometimes they move towards each other having, usually, quite destructive effects at their boundaries. That’s basic plate tectonics folks.

But back to Japan. When plates move towards each other different things can happen. Let’s focus on what happens when an oceanic and continental move together (remember those?). Oceanic plates are denser than continental and as a result are forced underneath the continental when the two move together. The friction as a result of this movement causes earthquakes.

So Japan is on unsteady ground, when one plate moves that could be the difference between life and death - but the danger doesn’t end there. We can split up the various hazards associated with earthquakes into two groups, primary and secondary.

Primary hazards are what happen as an immediate effect of the earthquake, such as the ground shaking or fissures opening up. Does that sound too bad? Well, let’s say for example you were standing in the middle of a field with no buildings or trees or other heavy objects towering above you around - the ground shaking wouldn’t be so terrible, in fact it could be a little fun. It’s the secondary hazards that tend to endanger lives.

Secondary hazards are hazards which happen as an effect of a primary hazard, such as buildings collapsing due to the shaking of the ground or gas mains being ruptured due to fissures opening. Large earthquakes in California usually have devastating effects because of the urbanised area, the hundreds of people bundled together and the large, very heavy, buildings. A similar sort of thing happened in Kobe, Japan in 1995. It wasn’t falling into fissures that killed so many; it was what was around them. Although Japan is renowned for its aseismic buildings and earthquake awareness it still wasn’t prepared when many of its gas mains and buildings collapsed or were ruptured, killing thousands. However, the tragedy of Kobe was that people were not prepared for it, meaning aid and rescue could not reach many affected areas in time.

You may have guessed it by now but tsunamis are also secondary hazards. When an earthquake happens in the ocean the ground opening will usually result in a tsunami. As you can see secondary hazards were the biggest problem for the recent earthquake in Japan. The tsunami which hit there has devastated the area and an explosion at the Fukushima nuclear power station has caused widespread panic. Although Japan was aware of what was going to strike it, it couldn't prevent it, which is why natural disasters usually have such terrible and fatal effects.

There is more I could say concerning the earthquake and its facts as well as its dynamics, but for now here are the basics to help you understand the whole ordeal a little better, I hoped it’s a helped a little bit.

For any more information concerning the earthquake and how to respond Google’s Crisis Response has almost everything you may need to know. Thanks for reading.

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IMAGE: Help Japan by Lost in Japan. Perdido en Japón