Re: Planet X: ZetaTalk ACCURACY

Greg Muncill wrote in message <3cb34614.35680616@news.mindspring.com>
> Greg Neill wrote:

>>
>> Rough guess?  Assume 1000km long chain of mountains,
>> 300km wide, 2km high.  Average density of rock, 5.5gm/cm^3.
>> How much work to lift a solid block that size to half
>> the height (1km)?  mgh.  I make it about 3x10^22 Joules.
>>
>
> Actually, that density is probably a little high for the crust.
> The average density is taking into account the higher
> density phases (iron in the core and minerals in the mantle)
> resulting from the high pressures inside the earth.  A more
> likely density would be 3.5-4.0.  The average basalt at the
> surface is about 3.0-3.3 and the average granite is 2.6-2.9.

I decided to err on the conservative side.  :-)


>
> Well I was getting quite a bit of heating when I was using
> Louie's formulas for going from seismic energy to tons of
> TNT and then doing some comparisons from there.  It turns
> out, though, that I think the energy/ton of TNT formulations
> are wrong at:
>
> <http://www.seismo.unr.edu/ftp/pub/louie/class/100/magnitude.html>
>
> His formulations for the erg energy calculations are correct and
> I get the same energy as you are talking about, 2X10^27 Joules.
> It turns out, though, this is equivalent to 55 days of total sun
> energy output, not 10 Years as I reported previously.

Sounds reasonable for where we started from.  Only recently
Nancy has confirmed that the crustal starting and stopping
all occurs in the space of an hour.  Yikes!  That pushes the
energy requirements up to about 1.5x10^30 J.  This does not
include the energy needed to start and stop the core
rotation.

>
> Further, if all this energy was converted to heat, it would yield
> 4.8X10^26 calories.  If this was spread out over the total crust
> (2.7X10^25 gm) it would only yield 18 calories per gram.  That
> would not be much of a temperature increase.
>

Well, rock has a specific heat of about 1000 J/kg/K.  So 18 cals per
gram would yield an overall crustal temperature increase of about
75K for the 4.8x10^26 cals.  That's if it would be evenly distributed,
which is highly unlikely.  The new figure of 1.5x10^30 J would yield
a temp rise of about 10,000K.


> Does this mean there would be no partial melting?  No.  We
> are only calculating Es, the seismic wave energy and as is
> pointed out in my reference above:
>
> "Note that Es is not the total "intrinsic" energy of the earthquake,
> transferred from sources such as gravitational energy or to sinks
> such as heat energy. It is only the amount radiated from the
> earthquake as seismic waves, which ought to be a small fraction
> of the total energy transfered during the earthquake process. "
>
> I am not a seismologist and it will take a little more
> digging to get a handle on the total energy of a
> Richter 15 event.  I am wondering whether the seismic
> moment, which is 20,000 times Es, is what we are
> after.

I believe that you are on the right track there.