Evening star., 1923-05-13
Artificial Earthquake
To Use Up Explosives

with relates to the waves sent out by
the shock.
There are three principal kinds OF
waves. Draw a circle to represent the
| circumference of the earth. Mark one
point "F," to represent the focus of
| the earthquake, and mark q couple
of other points "S." to represent sta
tions where it is observed or re-
corded. The three chief waves are:
| First those that go through the
| earth. and these are of two kinds;
| one a longitudinal vibration IN the
direction Of the motion, as in an
organ pipe, and this arrives at the
station first; then along the same
path comes the transverse wave,
which vibrates up and down at right
angles to the general direction. as
when one snaps a string, and this
reaches the station second. The third
kind of wave travels along the sur
face Of the earth, like the waves when
a stone is thrown into a pond, and
| they get to the station third. Still
| other waves start in the opposite di
rection from the focus and travel all
around the earth. They reach the OBJ
servation station last of all.
| The scientists have only very rough
estimates of the velocity Of these
waves, and for two chief reasons.
| In the first place. il is very difficult
to determine the exact time at which
an earthquake starts, SO the scien-
| lists have been able to figure the We
| locity only approximately. Then, too,
the quake takes place over long slip
maybe one mile, maybe twenty
miles-so that there is a succession OF
shocks and not at any one fixed point
When an earthquake is recorded IL
a chronological laboratory the record
Is mechanically made along a hori-
zontal line. First a tremor or slight
waviness of the line is noted. which
Is the preliminary or longitudinal
wave; second, the line begins to look
like the teeth on a saw, which Is the
secondary or transverse wave; and,
third, the line makes sharp jumps up
and down. which are the main waves
along the surface of the earth. These
last do the most damage. The seis-
mograph shows these waves with =
parallel mechanical time record. BY
measuring the time of the different
waves and knowing the velocity ap-
proximately the scientists calculate
how far off the earthquake is from
the observation station.
There are many other complications
which the scientists hope to study eff
fectively when the artificial earth
quake is set off in an abandoned mine.
They figure that If instead of hav-
ing the shock produced by a slip
along a long fault" they have the
shock start at a definite time and
from a definite point. the velocity
could be calculated very accurately.
The plan of operation Is to take.
say. twenty tons of explosive. or more
IL it can be had; put 1t in an old aban-
doned mine, and wall It UP so as to
confine the explosion and prevent its
being dissipated, as II might go wan
dering off through subterranean gal
leries, and then produce the explosion
by electricity at a definite time. 1t is
a series Of twenty or thirty seismo- .
graphs set up at different distances.
each with good clocks, SO as to get
the velocities very accurately.
The mine where this artificial :
earthquake Is to be set off has not yet
been selected. 1t will probably be ins
the Lake Superior region, or In the
Butte mining district of Montana. or y
perhaps in California.
One thing the scientists and gov
ernment officials emphasize Is ,thats
this explosion isn't going to do lot
of damage. and tear UP the earth. !es
many timorous persons will at once
conceive. They are already receiving /.
freak letters from cranks, some in
protest, as witness this anonymous .
communication. written In lead pencil
on a post card. postmarked "Monroepsij
N. T." which has been received. by
DR.. Washington: 50
"Sir: You say you are to dinimites /
this liveing planet What has this
God done to you that you wish to
chastise this planet with dinamite?-
to Passion play a stage earthquake?
Do you know this planet is the live
Ing God, that our fathers, the great
giants, died for, and our war all died
for. Irrigation. not dinamite. You
are treason ana murder, and aught tq
be arrested"