The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1884-08-14
WHY THE EARTH oUAKEs.
Forces that Are Pent Up Under Us and Woul
Smash Us If They Got Loose.

Forces that Are Pent Up Under Us and Would
Smash Us if They Got Loose.
Prof Merriman, Of Rutgers College,
while facts enough regarding the exte MT of
the earthquake of Sunday have not come to hand
to enable me to speak on the direction of the
earth wave or its peculiar features, as compared
with other earthquakes, yet something may be
said as to the latest convictions of students of
science on the nature of the earth below the
point any man can penetrate That may lead
us to guess intelligently at the cause Of earth
quakes
You know the long received theory Of the ma
ture of the interior of the earth was that it is
molten mass. and that we move around on a
crust enveloping the earth and caused by the
cooling of OF this mass ON the outside 1t is un-
donbtedly true that about thirty miles below
the earths surface the temperature is so
high that everything is in melted condition
We know this because We have learned that
every fifty feet we penetrate into the earth there
is an increase Of temperature of about one de-
gree, and at distance of thirty miles the heat
Is SO great that any substance we know of would
melt Perhaps the melted mass is in the form
OF liquid. That would be certain but for the
immense pressure on it. The pressure is esti-
mated at 10, 600 tons on a square foot OF course
scientific men cannot experiment with matter at
high temperature with a pressure of 0000
tons to square foot, SO we can only guess what
may be its condition. In talking about this
melted mass thirty miles under us, the term
water substance is used by biologists.
How great is the distance through this water
substance we do not know, but it is certain that
its density increases more and more, gradually
until the interior of the earth is solid, probably
from the uncomfortable pressure 1000, 2. 900. or
5000 miles from the surface. Sir William
Thompson has demonstrated that the earth must
have a core much denser than the land and
water we live on. He points out the fact that if
shell only thirty miles thick surrounded a
molten LIQUID mass extending from one side of
the earth through the center to the other side,
then the moon, through the law of gravitation,
would displace the liquid or gas in the interior
of the earth to such an extent that the eai this
crust would bulge out in the direction of the
moon, making tide in the solid crust of the
earth, as certainly as the skin of an orange
buges out when you squeeze the fruit between
the palms of your hands. And this would be
evident to us because the ocean tides would be
almost, if not quite, imperceptible to us To
withstand the attraction of the moon the earth,
Sir William says must be as rigid as steel.
$50 we have the theory that the crust of the
earth floats on and imposes an immense weight
on water substance, which is inconceiyably
hot. Now, as to the way an earthquake may be
caused. Suppose moisture triclxled gradually
year after year, through this crust into the
heated mass. In our atmosphere steam would
be produced Thirty miles below us the pres
sure is SO great that it is not likely tt at steam
could be generated One thing, though; the
pressure of 10000 tons to the square foot a
pressure exerted in every direction, would be in
creased Some effect must be produced down
there, and it is easy to see that if one place in
the earths crust is weaker than another near
the region where the water trickled in, then
the weakest place must stan the strain 1t is
not unreasonable to suppose that this pressure
below might be so great that the earths cover
ing shifted little to adapt-itself to the pres
sure from below. This shifting of the crust is,
in fact the earthquake.
81 believe this theory has the greater reason
on its side, because earthquakes are almost al