Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-05-01

with touching off California, and some
are recalling that similar coincidence OF
disturbances occurred in 1872 The stats
teal method is the only way OF solving
problems of this kind. so far 1t has
yet been applied to them. The eruptions
of Vesuvius and of Etna have long been
recorded and carefully compared; but with
out finding any consistent relations between
them. Any one is free to suppose, If he
wishes, that the tensions in the rocks of the
coast range were snapped by the tremors
from Nesuyius; but 1t must be remembered
that the tremors from Vesuyius are
much weaker than those which spread
away from a first-class mountain-frac-
ture earthquake; that the tensions under
the coast range must have been accumu-
latng for years past, and that during this
period various tremors, much stronger
than those lately caused by Vesuvfus, have
passed through the earth.
Density of the Earth's Interior.
AS. to there being any internal passage
communication between volcano In
one quarter OF the globe and earthquake
In another. as some seismic freethinkers
would have US believe, there is nothing
whatever to warrant the suppositon that
the earth has so loosely constructed an
interior. The density Of the earth as q
whole is twice as great as that of the aver
age surface rocks. like granite. The pres
sure of the exterior parts on the interior
is so great that, In spite of what we call
the rigidity of rocks, no cavernous spaces.
not even narrow cracks could be held
open at the depth Of ten twenty miles;
they would be squeezed shut The accurate
measurement of earthquakes in recent years
bears on this question. In the first place,
the tremorS that have a destructive strength
in the district of their source are perceptible
TO delicately poised instruments in all parts
of tie globe. The San Francisco shock was
recorded in Europe. The term earthquake
is therefore more fitting in a literal sense
than was ina gined when the word was
coined. Furthermore, the high speed with
which earthquake tremors travel through the
earth confirms the evidence OF other kinds
to the great density close texture OF
the earth's interior. Hence the idea of any
thing more than connection by tremors
between Yesuvius and San Francisco is
groundless. and the tremors of this kind
are extremely faint when they have trav-
eled 5000 miles more. In the second
place, the depth of the center from which
various earthquake shocks have proceeded
is but few miles. probably less than ten
in all cases, and this seems to mean that
when determinations take place at greater
depths the pressure of the superintendent
parts is so great as to make the deep-lying
masses slowly flow almost as If they were
fuid-and to this the high temperatures
there prevailing doubtless contribute eff
fectually. Hence at great depths there is
no chance for fractures to form. Under
SucA cOn0ltlOnS the possibility OF any sort
of connection between Fesuvius and San
Francisco, except by tremors is out of the
question. and In spite of condolences 1t
does not seem likely that the tremors
could have touched off the California
shocks.
No Tidal Wave.
1t Is noteworthy that the San Francisco
shock was not accompanied, far as re-
ports at hand testify, by any so-called
tidal wave" by any general change of
level OF the land with respect to the sea-
These tidal waves earthquake waves, as
they should be called, occur when crystal
disturbances either by eruption or by frac-
ture, take place beneath the ocean. a
small movement Is then given to the whole
everything body of sea water; as this move
ment swings away, waye-like, through the
deep ocean, 1t decreases in amount until 1t
comes into shallower water near shore;
there 1t increases again just swell In
crease into surf. Such waves are long and
fast-moving; they are faint on distant
coasts, though they may be recorded by
tide gauges; thus Japanese earthquakes
have produced perceptible oscillations of
the sea In the self-recording gauges of the
coast survey in Californian harbors
AS to changes of level, there were to be |
sure some reports of subsistence in va
rious Iowlands along the bay shore, but
this was probably the result of superficial
consolidation In loose deposits There is
as yet no report of the change OF level
along the rocky coast, such as took place |
in New Zealand in 1913 and such as has |
lately been described by Tarr of Cornell In
Alaska, as the result of the earthquake |
there in 1899; in Yakutat bay, about go |
miles northwest of Sitka, and not far from !
the great Malaspina glacier below Mount |
st. Elias, the change of level was even |
more than forty feet at certain points that |
being the greatest change of the kind that |
is automatically reported. 1t may be that |
something of this sort, but probably much |
smaller In amounts will yet be detected |
near the Golden Gate.
We shall probably soon be In possession |
of eircumstantial accounts of the earth |
quake. which will serve to settle many |
question that must here be left In doubt. /
the location of the epicentrum or place
above the center of the shock, the relation |
of the earthquake to the structural lines J
of the coast range, the velocity of trans