The Mitchell capital. (Mitchell, Dakota [S.D.]) 1879-1918, 1906-05-11
THEORIES AND CAUSES
OF EARTHQUAKES
May Be Act of God or Again
May Be the Attraction
of Planets.
MOST PLAUSIBLE THEORY
'oIcanio Erupti0ns and Fires in tn,
Earth's Center Probably the Prin-
cipal Cause of Earthquakes Like
the One in Frisco.

s'S ~
cipal Cause of Earthquakes Like
the One in Frisco.
An earthquake is a trembling Of the
earth's crust u to internal causes It
consists of a series of undulatory i'm
pulses or elastic waves, transmitted
through the rocks of the crust in some
what the same way that sound is trans
mftted through the air. An earthquake
tremor may be felt on the surface dis
tinctly and not in the lower levels of
a deep mine and vice versa. The size
of the area where the trembling is per-
ceptible probably bears some proportion
to the violence of the initial shock. The
great Lisbon earthquake of Its was
distinctly felt from Madeira to Great
Britain. or over the whole of southwest
Europe and northwest Africa. The
Charleston earthquake was felt from
northern Florida to New England, and
as far west as Iowa. or over an area
approximately LOO miles long and 500
miles wide. In the Lisbon earthquake
the tremors lasted about six minutes.
When an earthquake occurs beneath
the sea the ocean above spreads out
wardly in low. long waves thai travel
rapidly, but are slower than the earth
waves. An earthquake in the North
Pacific in June, 1896, caused a wave
forty feet high along the northerr
coast OF Japan tina did great damage,
over I..og9 persons being drowned.
commonest in California. and in gem
eral earthquakes are more often felt
near the coast than inland. Earth
quakes are usually commonest in re.
sions Of present or recent volcanic ac-
fIvtf no ri hCV q L. a.
proceed volcanic outbursts and cease al
the eruptions begin.
Some Theories on EARTHQUAKES.
Briefly stated the theories on tho
causes of earthquakes follow:
/. The theological theory held by an
unusual number Of persons, who believe
that the earthquake Is due to the d.
rect Intervention of Zoe as punishment
for sin or a warning to Righteousness.
h theory is of III greatest antiquity.
2. The mechanical theory which Inn
putes the earthquake to the slipping OF
rock strata n lays especial stress
upon the earth's falling in some places.
rising in others. II being agitated
everywhere.
hat the disturbances are due to fires
In the earth's center and to their fumes
n steam which force an outlet. In
the hot water, steam and gas elected.
n in the odors impaired to the
springs and wells they find evidence Of
the truth of their theories.
4. The astronomical theory, which
holds that the cause is to be found in
the attraction of the planets, derives
argument from the enormous weight of
the extraordinary Tides INC claims that
the attraction of the sun and the moon
operates pm the crust OF the earth as it
does on the great body OF water tina
it raises and lowers.
5. The electrical theory, whose fol.
lowers will deduce from the lights,
noise and velocities of their motions
n from comets and meteors that have
appeared simultaneously with the
earthquake, conclusions favorable to
the origin of the disturbance from the
subtle and universal agent, electricity.
6. The chemical theory which as
cribes the disturbance to fermenting OF
decomposing minerals. The believer in
the conversion of metallic potassium
by rapid Inflammation into common
potash in deep recesses of the earth
finds the salt petrous sandstone an ar
gument for his belief. in the chemical
theory OF earthquakes.
The ound which accompanies an
scribed more graphically thar by an
observer of the Charleston earthquake
OF 1886. He was at the time on the
second floor OF a lofty building in
Charleston when his attention was
vaguely attracted by a sound that
seemed to come from the office below,
and was supposed for a moment to b.
caused by the rapid rolling Of a heavy
body as an ire safe or a heavily laden
truck. over the floor. Accompanying
h ound there vas a ~perceptible ire
NOR of the building, not more mark ID,
however, than would be caused by the
passage of a car OF dray along the
street, Eor perhaps two or three sec
onds the occurrence excited no surprise
or comment. Then by swift degrees, oil
all at once-tt is difficult to say which
tho sound %dcepened. In volume, J the.
tremor became more decided. the ea1
caught the rattle of window sashes, gas
fixtures n other movable objects. g
The long roll d%eepened and spread into
an awful roar that seemed to pervade
at once the troubled earth and the still
air above n around. The tremor was
now a rude rapid CULVER. that agitated
h whole lofty, strong-walled build.
ing" Soon 1.-The floors were heavins
underfoot, the surrounding walls anG
partitions visibly swayed to and fro
h crash of falling masses Of stone and
brick and mortar was heard overhead
and without the terrible roar filed tn.
ears and seemed to fill the mind anc
heart. dazing perception, arrestink
thought until at last the up.
roar slowly died away in seeming dis.
stance. The earth was still, and oh! tn,
blessed relief Of that stillness!".