Tuesday, March 15, 2011

Myths and Facts About Earthquakes

With all that is happening in Japan I decided to do a little research on Wikipedia to find out what is really going on, mostly because I don't trust the news (funny how an open platform like Wikipedia can become more credible then the source for most people's information). What I will write here may not shed light on the Japan earthquake, but is more a reflection on what I discovered while reading. If you are curious to find out what I learned then keep on keeping on... after the jump of course.
  • The most surprising thing I learned about the earthquake in Japan was that the Richter scale is no longer used in calculating the magnitude of an earthquake. Now they use a scale called the moment magnitude scale. No one actually knows this because 1) no one talks about it, and 2) the values are the same as the Richter scale. A 9.0 earthquake in this new scale is similar to a 9.0 earthquake in the old scale. Even though it measures a slightly different quantity, you can be assured that number means that quake was a bad mo-fo. 
  • This quake is called a megathrust quake. I don't really care about the definition of the term, but it turns out that no other type of quake can generate the amount of energy needed for a quake of this magnitude.
  • There were a number of foreshocks associated with this quake. A foreshock is just like an aftershock except that it happens before the main event. A friend of mine was in Japan at the time of the main quake and he was notifying people about the foreshocks. I think he said one of them was a 7.2 or something. This was before the main quake. I remember thinking afterward if this would be linked to the great quake and apparently it was. Foreshocks and aftershocks can only be determined post earthquake.
  • In other foreshock news. The earthquake from Sumatra (The Indian Ocean earthquake and tsunami) had a foreshock that predated it by 2 years!
  • Tsunami's are interesting and scary at the same time. The tsunami from the Indian Ocean quake of 2004 was deadly for 2 main reasons: 1) the earthquake happened very near the shore to the nearest populated islands, 2) while most quakes result in ground moving horizontal, the ocean floor here actually moved many meters vertically which would displace an amazing amount of water. Those poor people had no chance.
  • Believe it or not, that wasn't even deemed a megatsunami. The largest one of those happened in the 1950's in Alaska because of a land slide. It generated a wave that was over 1700ft tall! That is scary. Unbelievably a man and his son managed to ride the wave to safety.
  • People in Tokyo had a little over a minute warning because the time of recording was 90s before the resulting earthquake wave would reach Tokyo. Even that minute saved lives.
  • A historic tsunami that completely and permanently submerged the prosperous Greek city named Helike could have been the basis for Plato's writings on Atlantis.
  • According to Wikipedia, the quake's magnitude is up to 9.0 which makes it the 4th most powerful quake since recording began in 1900. It is the strongest quake to hit Japan in that time as well.
  • According to reports, Japan got wider, it also moved closer to the US (by about 8ft), the Earth tilted 25cm more, the day is now shorter (by 1.8 microseconds), and a whole mess of other stuff happened.
  • The energy released from earthquakes can cause an effect where soil begins to act like a liquid in a process called soil liquefication. This can do all sorts of damage because everything that we build is on top of soil. Buildings can collapse, cars can sink, train tracks can bend, etc. Check out this picture:

I hope you learned some cool things about the earthquake in Japan and earthquakes and tsunamis in general. I certainly did.

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