Omaha daily bee., 1906-04-22
SCIENCE OF EARTHQUAKES
Causes Are Pointed Out and Discussed by
Father Rigge of Creighton,
ONE THING SURE, PREDICTION IMPOSSIBLE
Most Common Cause is Sudden sink
ing of the Surface on Account
of Contraction of the
Earth.
ONE THING SURE, PREDICTION IMPOSSIBLE

ton university, one of the prominent scien-
lists of the west, and once an associate at
Georgetown college OF Father Hagin, re-
| Gently called by the pope to Rome to be
director of the Vatican observatory, had
this to say yesterday upon the San Fran
cisco earthquake:
| Earthquakes may be due to various
| causes. The most common one is believed
to be the sudden sinking of the surface on
account OF the contraction Of the earth. The
earth Is continually losing heat, and must
therefore contract In volume. The surface
then becomes too large in proportion, like
the skin of a shrivelled apple from which
the interior has contracted In geologic
ages this shrinkage was on a much grander
scale and mountains wefe produced by the
process. As the earth is made up Of very
different materials the shrinkage is always
accompanied by a sinking of one part and
its rubbing against another. Both those
| actions cause tremors or earthquakes,
whose intensity. of course, must vary con-
siderably.
Another cause of earthquakes may be
due to the action of subterranean waters
in forming large caves, into which the
overhanging ground must fall sooner or
later, just as we see on small scale when
ditch has been dug and the ground filled
into it again.
Il Seepage of Water
"A third cause is owing TO the seepage
Of the water to the underlying rocks whose
high temperature changes the water to
steam and thus generates an enormous
pressure. which can be relieved only by
volcanoes or earthquakes.
"A fourth cause is said to be due to the
water of capitalization, as it is termed,
/ -, h. MI
have absorbed when they crystalIzed Is
like that which plaster of paris takes in
when it sets. The enormous heat deep
down in the earth must in the course of
time expel this water and change 1t to
steam, The pressure thus created is be-
lieved to be the most general cause Of
volcanoes and of earthquakes.
Earthquakes are certainly not caused by
sunspots, and If they We're. the difficulty
would only be shifted to the inaccessible
regions of the sun and we would ask
what caused the spot to break out on the
sun. Nor has the earthquake at San Fran
cisco any connection with the recent erup-
ton of Vesuvius. as far as our knowledge
goes at present. although / would not be
so rash as to deny the possibility of such a
connection.
Earthquakes also, are not caused by the
moon, as far as we know, nor by any force
outside of the earth, such az the conjunc-
ton of the planets, the favorite theme of
charlatan scientists. Earthquakes cannot
be predicted, and everyone that ventures
to predict one or claims to have predicted
one may unhestitatingly be classed as a
man craving notoriety at the hands of ig-
norant people.
Phase of Earth's Development.
A.
earths development. They occur in all vol
canic regions, but are by no means confined
to them. The western shore of South Amer
lea is especially subject to them. The in
terror of large continents is seldom visited
by earthquakes, and it is very unlikely
that Omaha will ever suffer from such a
visitation. An additional protection Is af-
forded our city by the yielding character
of the soil, through which shocks are prop
sgated only with difficulty The tremors
caused by distant earthquakes are, of
course noticeable IN Omaha, but they need
never cause alarm.
'"rhe instruments used in observing and
recording earth tremors are called seis.
mographs. Father Algue's instrument.
exhibited I'm the Philippine observatory
at the Worlds fair in St Louis. was a
good model 1t consisted or a pendulum
about 200 pounds in weight and ten or
/ twelve feet long. IL was supported by
: strong arch Of masonry When the
; ground shakes the inertia Of the heavy
I pendulum holds it's place. and the ground
4 actually moves from under It, A pointer
below the pendulum traces its apparent
! motion. that is, the real motion OF the
I ground, on a piece of paper moved for
= ward by cloclXwork. When this motion IL
, greatly magnihed by delicate levers the
, instrument Is called microseismogrdph
5 Generally two systems Of levers are used
$ in order 10 record the motion of the
b ground in the meridian and at right
. angles thereto, Another large weight
& supported in horizontal equilibrium anc
e making use OF the same principle OF
inertia registers the vertical motion Of
the ground. The three components thus
n obtained must be recOmposed in order e
J. md the actual motion in space. Tn,
1 time is indicated by the motion of tn,
Z paper. Sometimes the beginning OF th,
G tremor Is recorded by an instrument re
semblng a tack hammer which has
). nne point resting upon a nail; the slight
/, est motion in any direction dislodges m
!, hammer. marks the time and sets tn
other seismographs IN motion. when, a.
!. may be desirable, a needless amount o
paper Is not continually being rul
through the machine.
. 'The Creighton University observatorl