The Anderson intelligencer. [volume] (Anderson Court House, S.C.) 1860-1914, 1875-11-11
THE Origin and Extent of. Earthquakes.

Prof. Raines contributes the following
very interesting letter to the Augusta
,C6nstitutionalist, which gives a scientific
explanation of the recent earthquake:
.ldi AUGUSTA, November, 1875. :
Earthquakes are disturbances of the
crust of the earth, caused by some action
of the interior fiery liquid, which consti-
tutes the great mass Of the globe. This
crust constituting the hardened shell and
surface, is probably not over an average
of fifty miles in thickness, and does
not bear a large proportion or
thickness to the earth itself, than
covering of paper. oyer ball two
feet in diameter. Hence, it. is easy to
understand that any disturbance what
ever in the melted mass below would
probably cause some waye-like move
ment, vibratory, action in the rocky strata
of this thin crust. The causes Of such
disturbances are probably of several
kinds-such as the infltration of water
through cracks, forming vast volumes of,
imprisoned steam, of enormous tension,
|. which would necessarily seek to escape
through some vent, producing volcanic
explosions and eruptions. The gradual
/ cooling downiof the earth itself would.
cause disturbances by. the decreased size
Of. the great interior mass, and the in;
crease Of the crust of crystalization of
previously melted matter. Thus there
would be produced tendency of the
crust to wrinkle up, and this would cause
O gradual increasing tension on the rocky
strata, which at times would give way at
the weaker places; the noises Of the
cracking rocks would sound like the rolf-
ing of wheels over the pavements, or like
the rumbling of distant thunder, accom-:
panied with vibration or vertical jar
ring. Again, should the atmosphere be
considerably lessened in height over an
extended area, indicated by what's called
low barometer, the decreased, pressure
over such surface might cause an upward
! tendency in the liquid mass below thus
great storms are not unfrequently accom-
i panied with earthquakes. The electrical
band magnetical forces of the earth ITSELF
or in connection with those mighty ex-
| .pl0sions in the sun, which cause a power
. ful disturbance of these forces in the
earth, may perhaps be at times, efficient
cause. for perturbations in the forces
. WHICH, hold the, crust in equilibrium. II
}, does not follow that an earthquake fell
: at any particular locality. may have there
originated 1.-THE focus ofaction may have
been many hundreds of miles away, anc
the wave of disturbance like tidal wave
, of the sea. may have travelled 6fer an ex
tended area. Sounds are, far better con
Quoted by rocky. masses thanrby the air
and travel much greaterdistances. Vic
,llent earthquakes precede or accompany
|, +volcanic eruptions, hence the latter ART
looked upon as safety valves, giving out
let to the imprisoned cases.. All .coun
tries having active volcanoes are iabl'
to repeated earthquakes, and the inhabit
'iEants have great dread of. their effects,
Whilst in Mexico, our army found th'
; people much. more effected by an earth
quake than ourselves: . indeed our, re
J. rspect for them increased with. our stay
Perhaps thereis scarcely q house of an,
size in the city of ldexico, whose wall
; have not been more Or less disturbed, an,
numerous cracks in, the cathedrals an,
:: ,aqueducts give indications of repeate1
action. i,r. ..st..I .;i,t, :a.;-.i t;ij
, The jarring vibratory earthquake ex
perienced1 last night, probably over
, large portion cf the State, I think proba
) bly,, was due to the second of the cause
enumerated. ~ .