A Tale of Two Scales

03/17/2011
By

TOKYO (majirox news) – What does it mean to go from 8.9 to 9.0? By now everyone knows that the March 11 Japan earthquake was revised from 8.9 to 9.0 on the Richter Scale.

However, Japan uses another measurement called the Shindo Scale, also known as the Omori Scale, which was created by Fusakichi Omori in 1894. Omori was a professor of seismology in the Imperial University of Tokyo and president of the Japanese Imperial Earthquake Investigation Committee. This scale measures the intensity of an earthquake at a given location. In other words, what people feel at a given location. The Shindo Scale ranges from 1, which is a slight earthquake that may be felt by only a few people, to level 7.

The Richter Scale, invented by Charles Richter in 1934, measures the magnitude of an earthquake – the energy an earthquake releases at the epicenter – and is based on a logarithmic scale (base 10). Each whole number increase on the scale means the amplitude of the ground motion increases ten times. In other words a magnitude 6 quake would result in 10 times the amount of ground shaking as one of magnitude 5.

The chart shows the comparision of the two scales


GOING FROM 8.9 to 9.0

An increase from 8.9 to 9.0 doesn’t sound like a big difference. After all, that’s only 0.1 difference. But what does that really mean?

An 8.9 earthquake is equal to blowing up 674 million pounds of TNT. At 9.0 that rises to 954 million pounds. Compare this to the Mount St. Helens explosion in 1980 which equated to 20 million pounds.

Shakers of this size are extremely rare and there have been only 5 in the world of this intensity since record keeping began in 1900 and the first ever to hit Japan

jpeters@majiroxnews.com
Joe Peters is a writer for Majirox News and also runs a Tokyo-based executive search company.
Link: www.isearchworldwide.co.jp
http://www.majiroxnews.com/2011/03/13/short-take-meltdown-madness-grips-fleeing foreigners/

http://www.majiroxnews.com/2011/03/15/in-japan-crisis-foreigners-turn-to-social-

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One Response to A Tale of Two Scales

  1. Jacques Cuse on 06/22/2011 at 9:16 pm

    L.S.,

    Please have a serious look at this:

    No shocks of 8.9 or 9.0 on the Richter scale whatsoever, neither a 7 on the Shindo scale…

    Which leaves us with some serious questions about what really happened…

    Maybe it’s Jim Stone who got the answers. Please check it out for yourselves:

    Happy reading!

    Best regards,

    JC

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