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Re: Order of magnitude

• To: <seaint(--nospam--at)seaint.org>
• Subject: Re: Order of magnitude
• From: Christopher Wright <chrisw(--nospam--at)skypoint.com>
• Date: Tue, 14 Sep 99 16:12:00 -0500

```>* The biggest earthquakes are (8. x) Righter magnitude and
>10000x20x1000=2x10^8.  You owe me a beer Chris.
I think I owe you a recommendation for a beer. You got fairly close
because you got fairly lucky. ;-> So try Summit Extra Pale Ale--lip
smackin' wonderful.

correlation and the heat of combustion of TNT (=820.7 Kcal/mol @ 227.12
g/mol = 1.37 joules/Ton. 4186 J/Kcal and 10^7 ergs/joule gives a heat of
combustion for TNT of 1.37E10 joules/ton) and came up with the following
table (Check it out with a monospaced font like Courier):

Magnitude	  Energy     	  Equivalent
(joules)	     Tons of TNT	  Log(Ton)
4         	6.31E+10	            5	       0.66
4.5	       3.55E+11	           26	       1.41
5	         2.00E+12	          145	       2.16
5.5	       1.12E+13	          818	       2.91
6	         6.31E+13	         4598	       3.66
6.5	       3.55E+14	        25858	       4.41
7	         2.00E+15	       145410	       5.16
7.5	       1.12E+16	       817702	       5.91
8	         6.31E+16	      4598276	       6.66
8.5	       3.55E+17	     25858009	       7.41

You get fairly close for the strong earthquakes but the agreement gets
worse for weaker ones. The hooker is the 11.8 term in the magnitude
correlation which affects the proportionality. Enjoy that Summit, but
don't forget that the Richter scale isn't defined by an energy release
rate but by a standardized seismograph reading.

Christopher Wright P.E.    |"They couldn't hit an elephant from
chrisw(--nospam--at)skypoint.com        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw

```