Re: Wave Intensity vs Energy

[John Denker <jsd@MONMOUTH.COM>]

> "Bernard G. Cleyet & Nancy Ann Seese" wrote:
> >
> > "Because of the logarithmic basis of the scale, each whole number
> increase in
> > magnitude represents a tenfold increase in measured amplitude; as an
> estimate of
> > energy, each whole number step in the magnitude scale corresponds to
> the release
> > of about 31 times more energy than the amount associated with the preceding
> > whole number value. "

Then at 02:17 PM 10/18/00 -0400, James McLean wrote:


> Hmm, I guess E propto A^2 applies for linear (in the sense of Hook's
> law) media.  Now does that mean that earthquakes are sub-linear or
> super-linear......

No, I don't think there's any significant nonlinearity.

===
More generally:

We seem to be comparing applies and oranges here.  Think about the
dimensional analysis.  The subject line mentions intensity and energy;  one
is simply related to amplitude while the other is not.

The Richter scale cannot measure both amplitude and energy;  a
low-amplitude wave can carry arbitrarily much energy if it continues long
enough.  There cannot be any simple relationship between magnitude and
duration, because the waves spread out with distance.

The destructive power of an earthquake
 -- obviously depends on amplitude, and
 -- secondarily depends on duration.

The fairly-recent Mexico City earthquake was infamous for having an
unusually long duration.