The Western news. [volume] (Libby, Mont.) 1933-current, 1935-11-14
By DR. Harold w. Scott,
tGeologist State Bureau of Mines and
Geology, Montana School of Mines,
Butte, Montana.

Throughout the history of civilization
no natural phenomenon has been sucl
a terror to mankind as the earthquake
It's mysterious nature, its frightful de
structlveness to property and life ant
its sudden unexpected occurrence ac
companied with the screams of tn,
hysteric and injured instill untold fea
in the human mind
We find records of earthquakes il
the Old Testament, Thou has made tn,
earth to tremble; thou hast broken it
heal the breaches thereof; for i
shakethn Again, in the one hundred
and fourteenth Psalm, aThe mountain
skipped like rams, and the little hill.
like lambs. =. Tremble, thou earth
at the presence of the Lord"
Only few years ago superstitious
people of the world attributed the
shaking of portions of the earth to the
wanderings of animals beneath the
surface, In India it was a large mole
IN Japan, large spider, though in
modern times this has given place to
giant catfish, in China, a subterran-
can hog; by some of the old philoso
piers earthquakes were thought to be
due to underground fires, gases, or
winds. Even to this day many people
are little better informed in regard to
the cause of earthquakes. Recent
rumors of volcanic ash and fire issuing
from assures, forty-foot crevasses. the
freezing of geysers in Yellowstone Park
resulting in great explosion in Helena
Valley are all indications of our de-
sire to believe the ridiculous and pre-
posterous.
Some Great Earthquakes
On November /, 1755, deep sound
resembling thunder issued from the
ground below Lisbon, Portugal, and
almost Immediately followed a quaking
which destroyed most Of the city. In
few minutes $1,000 people perished
The city czught on fire. The sea re-
tired from the land, carrying boats
with it, only to return in few mo-
ments In wave sixty feet in height
to complete the destruction Of the city
On April Is, 1906, California ex-
perienced the worst earthquake in the
history of the state The area of de-
struction was about 400 miles long and
about so miles wide on either side of
the San Andreas fault. In San Fran
cisco about 500 people were killed and
al least $25O, 900, 900 property damage
resulted from the quake and the fire
which followed it, destroying most of
the city.
The most recent disastrous quake
occurred in Japan on September /, 1923,
when $4,000 people lost their lives.
128,0O0 houses completely collapsed, and
447, 600 houses were burned Great fires
often follow major earthquake be.
cause the water mains break, leaving
the city defenseless against the fires
which start when stoves or lamps are
overturned, electric wires break and
short circuit, or from other causes
1t is obvious that the Helena earth
quake was of moderate intensity when
compared with some of the great
quakes Of the past
Cause Of Earthquakes.
The progress of the science of geolo-
gy has produced evidence that the
major earthquakes result from sudden
yielding to strain in the earth's crust
The rocks in the crust are constantly
required to adjust themselves TO ex-
cessive pressures from above or lateral
pressure from the side. If this adj
jnstment takes place within six miles
or SO Of the surface it is accomplished
by one rock mass moving against an
other. The zone along which the
movement takes place is fault The
actual slippage is almost instantaneous
and causes a severe Earring of the
nearby region. The resulting jar is an
earthquake. The waves which are set
up by the jar are propagated through
and around the earth. In the area where
the faulting occurs the waves come to
the surface and have tendency to
project loose objects from the suface
just as a marble lying on floor will
bound into the air several inches by a
tap of a hammer upon the floor some
distance away
Volcanic activity is also recognized
as cause of some earthquakes. How
ever, such quakes are not of the first
magnitude and the disturbed area is
very small. Earthquakes caused by
volcanoes may destroy houses which
are situated directly above the disturb
ance, but the waves will not be felt
for more than very few miles in any
direction. The volcanic earthquake is
localized, the waves set up do not
travel over wide areas, and the focus is
very shallow.
The fact that the Helena earthquakes
send waves far out in all directions is
sufficient evidence to consider their
cause as slippings along fault
Seismographs.
Earthquake waves are recorded on
delicate instruments called seismo-
graphs. A seismograph consists of at
least three parts: one which remains
steady during the earth movements; a
second which consists of frame from
which the steady mass is suspended
and third part, recording device
consisting of revolving drum or plate.
The recording device in addition to its
own revolution also moves in accord