This Is Not Good
Woke up this morning to the news of an 8.9 earthquake off the coast of Sendai, Japan; for reference, Richter scale is logarithmic, with each full integer representing a ten times increase in energy amplitude [see the comment below]. The Loma Prieta quake that hammered San Francisco in 1989 was a 6.9, meaning the Sendai quake was literally 100 1000 times stronger. Aftershocks of this quake have measured as strong as 7.1 and the news of the devastation just keeps getting worse.
Come back Monday for web-based laugh-chuckles. In the meantime, keep thought for those affected around the Pacific in whatever way you do; watch out for charity scams, and maybe say thanks to the engineers and architects that designed all the structures that didn’t collapse.
A quick correction: The Richter scale is logarithmic (base 10) in _amplitude_, not energy. The energy doubles every 0.2 on the scale, meaning that the difference between Loma Prieta and this one is a factor of 2^(2.0/0.2)=2^10=1024.
(Don’t worry—I had to double-check that last night after CNN tried to convince us that restating the magnitude from 7.9 to 8.8 was a factor of 1000. I hardly have these things memorized.)
Otherwise, what Gary said. Try to keep on top of things, and if you have friends or family in the area, I hope they’re alright.
By Colin Morton on 03.11.11 11:22 am
It’s a thing which, honestly, makes the Richter scale at odds with every other self-respecting logarithmic scale in use; for instance incrementing by 10 any amount expressed in dB signifies multiplying the energy by 10, even when the thing being measured, like electrical tension, is not linearly related to energy. By comparison, multiplying the energy by 10 in the Richter scale comes down to adding… about 0.66.
(engineer ranting off)
By Pierre Lebeaupin on 03.12.11 8:12 am
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