The morning news. [volume] (Savannah, Ga.) 1887-1900, 1897-07-20
SUBMARINE EARTHQUAKES.
Beneath the Oceans Surface They
Are similar TO Those on Land.

From the 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 so on beneath the sea. There was
thus melancholy appositeness in his
remarks, for each successive telegram
from India brings worse and worse ac-
counts of the recent seismic disturbance
there. Large districts have suffered more
or less severely about Calcutta, Madras
and Bombay. but the devastation in AS
sam is now stated to be on a far greater
scale; and it is probable that the worst is
not yet known.
But Prof Milne. as we have said. was
discussing a more comprehensive question
the movements that take place in the
silence of the central sea-" We have long
been aware that even here the earth Is not
absolutely at rest. Tiny organisms fall,
like a perpetual dTizzle, on the ocean floor;
earth dust, yet more minute sinks grad
ually down through the water, but this
ooze accumulates with extreme slowness.
Besides this, the floor itself may be up
lifted or depressed, but these movements
also had been supposed to be very gradual
so much so that they could not be de-
tected, could hardly be inferred directly,
from any observations made by man.
Prof Milne, however, shows that there
are occasionally very significant hints of
what is going on, and that now and then
nature moves more abruptly than some of
US suppose. Submarine cables indicate
unexpected disturbances; now the gutta
percha is melted. as II by heat; now the
cable is broken as though by a strain;
now it appears to have been buried by
mud slip
There are, it seems two sets of causes
which produce movements beneath the
surface of the sea. The one is the slow
fodings, fractures and crushings of the
crust-causes on land which have produced
mountain chains, and are conspicuously
recorded on their rocks. The other is the
effects of erosion and sedimentation. The
removal of material from one place. as
from a seaworn coast, and the deposit of
it in another produce exactly the same re-
suit as the piling up of materials else
where would do-namely, unstable con-
tours, which may ultimately cause move
ments of various kinds. In other words,
there may be landslips below the water
just as much as there may be above it,
and from not dissimilar cause Both these
kinds of influence probably affect larger
areas. There is a third, but more local
lied, modifier of the sea bed-the sub-ma-
rine volcano. All three may produce earth
quakes the first especially. Bent rocks
may at last break under the strain; one
or both parts of the divided mass may
start forward as it were, with a jump;
myrads of tons of rocks are set in notion
and a shudder is propagated through the
earth's crust, 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
- . H..
bling process continues, new slips may oc-
cur along the line of fracture and fresh
shocks be propagated through the crust.
One special object of Prof. Mines lect-
ure was to point out the circumstances in
which 9ese disturbances are most likely
to occur An earthquake and movement
of some kind stand in the relation of effect
and cause. Sometimes this movement is
of an explosive character, and the shock
is directly connected with volcanic action
but-perhaps more oftenA-the latter also
stands rather In the relation OF eenSe-
quence to movements tending to wrinkle
the earth's crust. Prof Milne, during his
residence in Japan-a veritable land of
earthquakes-took some pains to ascertain
whether the shocks were started in the
mountain region or beneath the sea, and
found that out of 4l9 shocks less than one
sixth had originated inland, more than
half beneath the ocean, and the rest near
the coast, and even of these a good many
had come from the sea. Besides this, Re
has observed that wherever the land de-
sends rapidly beneath the surface of the
water, whether from the coast line or into
an ocean basin, there earthquakes are
likely to originate, while gentle slopes
are rarely the sites of disturbances. Slip
ping 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 In
dian ocean there is, we may remark, a
rapid deepening of the sea bed, and on
either side much accumulation Of mate
rial. Whether the recent earthquake has
any connection with the swatch of no
ground" cannot be known till moro pre-
else details have been received and COM
pared, but Prof. Mines remarks on the
general question show that this IL not inn
possible.