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# Re: Order of magnitude

• To: <seaint(--nospam--at)seaint.org>
• Subject: Re: Order of magnitude
• From: "Greg Smith" <strusup(--nospam--at)gte.net>
• Date: Tue, 14 Sep 1999 12:06:19 -0500

```Christopher Wright wrote:

According to
'Nuclear Reactors and Earthquakes' the biggest earthquakes release energy
equivalent to 10000 20 kiloton nuclear bombs.

* The biggest earthquakes are (8. x) Righter magnitude and
10000x20x1000=2x10^8.  You owe me a beer Chris.

Seismic Design of Building Structures 5th ed. by Michael R. Lindeburg, P.E.
pg.12 says:

"In 1956, Gutenberg and Richter determined the approximate  correlation to
be as given in Eq.8.  E is the energy in ergs.  Although there have been
other relationships developed, Eq.8 has been verified against data from
underground explosions and is the primary correlation cited.

Eq.8       log(10)E=11.8 + 1.5M

The radiated energy is less than the total energy released by the
earthquake.  The difference goes into heat generation and other nonelastic
effects,  which are not included in equation 8.  Little is known about the
total energy release."

Greg's comment cont.: The basic question to the post is now: how many joules
are released in the explosion of a ton of TNT?  I'll bet if you convert it
to ergs then eq.8 will verify it.

Greg
-----Original Message-----
From: Christopher Wright <chrisw(--nospam--at)skypoint.com>
To: seaint(--nospam--at)seaint.org <seaint(--nospam--at)seaint.org>
Date: Monday, September 13, 1999 3:30 PM
Subject: Re: Order of magnitude

>>The Richter scale is based on the equivalent energy in tons of TNT.  So a
>>7 on the Richter scale means 1X10^7 tons of TNT.
>For what it's worth (could win you a bar bet some day) The Richter scale
>is an arbitrary one based on a standard (Richter's standard) seismometer
>amplitude at a distance of 100 km from the epicenter. According to
>'Nuclear Reactors and Earthquakes' the biggest earthquakes release energy
>equivalent to 10000 20 kiloton nuclear bombs. The 1906 San Francisco
>quake release was about 10^16 joule.
>
>I think I need to get out of the office more often...
>
>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
>
>

```