The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1897-07-17
EARTHQUAKES IN THE SEA.
Results Produced by Volcanoes and
LnndsIips Under the Water.
London Standard
London Standard.

Earthquakes formed an important topic
IN the interesting lecture which Prof. John
Milne delivered to the Royal Geographical
society last night, though he was dealing
with the wider subject of the changes
which go on beneath the sea. There was
thus a melancholy appoSiteneSS in his re-
marks for each successive telegram from
India brings worse accounts of the recent
seismic disturbance there. Large districts
nave suffered more or less severely about
Calcutta, Madras and Bombay, but the dew
aStation in Assam is now stated to be on
a far greater scale, and it is probable
that the worst is not yet known. But Pro-
fessor Milne, as we have said, was discuss
ing a more comprehensive questionable
moXeements that take place I'm the silence i2
aware that even here the earth is not alb
solutely at rest. Tiny organisms fall, like
a perpetual driZzle on the ocean floor;
earth dust, yet more minute, sinks gradual
ly down through the water, but this ooze
accumulates with extreme sloWness. Be
sides this the floor itself may be uplifted
or depressed but these movements also
had been supposed to be very gradual-sO
much so that they could not De detected,
could hardly be inferred directly, from any
observations made by man. Professor
Milne, however, shows that there are oc-
casionally very significant hints of what is
going on, and that row and them nature
moves more abruptly than some of Jus sup
pose. Submarine cables indicate uHeXpect-
ed disturbances; now the gutta percha is
melted, as if by heat: now the cable is
broken, as though by q strain; now 1t APP
peers TO have been buried by mudslip.
lnor6 are, II seems, TWO sets OF causes
which produce movements beneath the sur
face of the sea. The one is the slow fold
ings, fractures and crushings of the crust
causes on land which have produced noun
tain chains, and are conspicuously recorded
on their rocks. The other is the effects of
erosion and sedimentation. The removal
worn coast, and the deposit OF 1t In an
other. produce exactly the same result as
the pilng up of materials elsewhere would
do-namely, unstable contours, which may
ultimately cause movements of various
kinds. In other words, there may be land
slips below the water just as much as there
nay be above it, and from not dis
similar causes. Both these kinds OF infiu-
ence probably affect larger areas. There
is third, but more localized, modifier Of
the sea bed-the submarine volcano. All
three may produce earthquakes. the first
especially, Bent rocks may at last break
under the strain: one both parts of the
We're, with jump; myraids of tons Of
rocks are set in motion, and a shudder is
which, when it originates beneath the
ocean, may shatter cities on reaching the
land, and may raise huge waves, that come
sweeping along the coast, bringing death
and destruction to the lowlands. The first
jerk may not be the only one; again and
again, if the crumbling process continues,
ture, and fresh shocks be propagated
through the crustJi gal
one special object of Prof Mines lecture
was to point out the circumstances in which
these disturbances are most likely to occur.
An earthquake and mvement of some kind
stand in the relation of effect and cause.
Sometimes this movement is of an eX-
plosive character, and the shock is directly
connected with volcanic action but-per
haps more often--the latter also stands
rather in the relation of consequence to
movements tending to wrinkle the earths
crust. Prof. Milne during his residence in
Japan-a veritable land Of earthquake
took some pains to ascertain whether the
shocks were started in the mountain re-
gion, or beneath the sea, and found that,
out of 10 Shocks, less than one-sixth had
originated inland more than half beneath
the ocean, and the rest near the coast, and
even of these q good many had come from
the sea. Besides this. he has observed that
wherever the land descends rapidly beneath
the surface of the water, whether from a
coast line or into an ocean basin, there
earthquakes are likely to originate while
gentle slopes are rarely the sites of dis
turbance. Slipping of materials also occurs
much more easily in the former case, so
that here disturbances of all kinds become
more probable. In the northern part of the
Indian ocean there is, We may remark.
rapid deepening of the seabed and on either
side much accumulation of material.
Whether the recent earthquake has any
connection with the swatch of no ground
cannot be known till more precise details
have been received and compared but Prof
Mines remarks on the general question
show that this is not impossible.