The sun. [volume] (New York [N.Y.]) 1833-1916, 1915-01-31
Elihu Thomson Misquoted on Explana.
ton of Recent Upheaval in Italy,.
Conflicting Theories of Scientists

on the earth's surface has little II any
influence In determining the time OF
earthquakes. Logically no other
conclusion could be expected in the
case OF tectonio earthquakes, for the
attraction of the sun and moon is uni
formly distributed over large areas OF
the earth's surface and therefore can
directly cause very little difference In
the stresses on opposite sides OF faults"
There has been a popular notion that
earthquakes are always identified with
volcanic perturbations, not necessarily
with eruptions: but this theory is no
longer held by science Prof Harry
Fielding Reid OF Johns Hopkins Uni
versity. says:
THE idea that volcanic outbursts
were always accompanied by earth
qunlSes and that generally tho regions
Of the earth where volcanoes were com
mon were also regions OF many earth
quakes led 10 the belief that these were
but two phases of the same phenomena
and that earthquakes themselves were
due 10 explosions in the fluid interior"
Later the idea that many earth
auakes are Independent OF volcanic ac-
ton and that they are due TO move
ments OF some kind in the crust OF tho
earth became stronger. and in 1850 &.
T. Naumann divided earthquakes into
two classes. the volcanic and the tee
tonic. the first being due TO volcanic
explosions and the second to move
ments in the rock mass
THE importance OF tho latter Cause
has become. more and more apparent.
so that now we feel quite certain that
all the really great earthquakes are Of
the teCtonic class. and that earthquakes
connected with volcanic outbursts are
OF comparatively little Importance II
is always found that volcanic earth
quales, although they may be very vio-
lent in the immediate neighborhood OF
their origin. die out at n very short
distance from It, and. indeed. this is
one criterion actually used 10 determine
IN which class a particular shock should
be put"
One thing Is certain. this world Of
ours has been progressively chilling for
millions Of years at least, and its crust
has undergone systematic shrinkage ac-
cordingly. In doing this tho outer lay
ers have been wrinkled and disrupted
by this process under the combined
forces OF contraction and external and
internal pressures.
II IL also firmly established, accord
ing to Prof. Reid. that since the be-
ginning OF geological history the crust
of the earth has been In continual
movement, rising in one place, sinking
In another. here squeezed into folds
there somewhat stretched" Prof A A.
Nicholson OF the University Of Chicago
has established the fact that the solid
surface of the earth is subject 10 the
same ebb and fiow as are the tides "
the ocean, although TO a lesser extent"
This confirms Prof Reds declaration
thai II mas long been recognized tnat
earthquakes were due to rapid to
and fro motion OF the earth. and that
these vibrations were propagated from
centre Of disturbance. II has also
been recognized for some time that
these vibrations must be OF the nature
of waves, elastic aud not gravitational
waves, and the question which presents
itself TO us is: What produces these
waves?"
Here is found the superficial or the
immediate promoting cause OF most
earthquakes, those OF the tectonic va
rety In which the rock mass moves.
In the case Of the California earth
quake OF 1905 the disturbance was
Andreas fault. and the rock of that
region slipped throughout a distance
OF go miles, and subsequently Il was
determined that the two sides OF the
fault had been displaced relatively to
each other by amounts varying from
maximum OF 81 feet TO an unascer-
tanned minimum" Tho energy liber-
ated thus within few seconds OF time
during the period Of the greatest shock
represented work done equivalent to
raising to n height OF one foot 65.00O,-
000, 000, 900 tons
According to William Herbert Hobbs
earthquake belts are those portions
of the earth's crust which in recent
times have suffered the greatest move
ments in n vertical direction-they arc
the most mobile portions OF the earth's
crust" The same authority says that
the region Of the Caiaprian earthquake
OF September, 1905, the district south of
the recent Italian catastrophe, had
earlier been studied by the biologists:
and the fatal tremors OF 1905 we're
manifested directly along the lines OF
the previously determined underlying
| faults.
| Tectonlc or structural Establishments
OF the rock mass IN this region, and
north and south OF II. had before and
since occasioned disastrous earth
quakes. Indeed, II now comes to light
that the region OF Asturias. in north
ern Spain, suffered an earthquake on
January .. eleven days before the seismic
| upheaval which has SO recently stricken
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