Re: Quake inflation

While spitting out some home-made cheese, I heard Rosalind Mitchell
<rcmitchell@xxxxxxxxx> say

J. P. Gilliver (John) wrote:

In message <62ma3qF245qcuU1@xxxxxxxxxxxxx>, Sebastian Lisken
<Sebastian.Lisken@xxxxxxxxxxxxxxxxxxxxxxxxxxx> writes
[]
much importance. Partly the reactions here put me right. I have even
less earthquake experience than most, maybe that's one reason for my

I have none. (That I'm aware of.)

reaction. The only one experience I did have was one of about mag 4 I
think, it happened in the Aachen region (over 200 km away), in the small
hours, but I had been up late and was still half-conscious. I felt what
I thought was a strong wind moving the house (not a stone house, mind)
that briefly got me back from semi-consciousness, then the next day the
news made me realise what it had been. I thought maybe 5.2 would make
a serious difference, now it seems it doesn't quite yet ...
[]
I believe it's a logarithmic scale - x10 per whole number, I think. (Not
all log. scales are x10 per unit - astral magnitude is one that isn't,
for example.)

And proper logarithmic scales are x2.718... per whole number, surely?

That depends on how you define *proper*. "e" or 2.718... is the base
of the "natural" logarithm, but it's perfectly reasonable to use other
numbers, such as 2 or 10 as the base of a logarithmic scale. I
wouldn't consider them to "improper" in any way.

When you are using a logarithmic scale to measure natural phenomena,
it makes sense to choose a base that will give you an easy-to-use
scale. For example, if the strongest earthquake ever recorded is,
say, 10,000,000 times more powerful than the smallest detectable
earthquake, it makes perfect sense to use a logarithmic scale to the
base 10, define the smallest detectable earthquake as strength 1,
something ten times more powerful as strength 2, and so on. The scale
then goes from 1 to 8 - convenient and easy to understand.

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