1872..
OLDHAM AND MAHET CACHAE EAETHQTJAKE.
267
And where apertures are provided (at the same moment almost)
by the earth-fissures, the rising liquids will, through these, find
easy vent.
As respects the height in the fissures //' to which the water of
the water-bearing or ooze-bed o o can rise when the mass C is
Fig. 5. — Diagram iUustrathig the Rise of Water in tJie Fissures.
pressed down upon it by the vertical component of the wave-motion,
if V = the maximum velocity of the wave-particle, which is in the
contrary direction, impressed upon the mass C, Avhose weight is =
W, then the impressed work accumulated in C is
TJ — 1 _ V2 •
'7 ,
and as the mass C is not free to move in the direction B A, the
horizontal component of the wave's motion, whose wave-path is
A B, makes the angle B with the horizon ; i. e. 6 is its " angle of
emergence."
Then, in the vertical, the impressed work is
but
V2
(V sm df = 2g h, or h = i—,
h being the height due to the velocity in the vertical.
Hence the minimum height to which the water from the ooze-
bed will be raised by the depression of the mass C is =: 7i in feet,
provided there is enough water in the ooze-bed, and that the latter
is easily compressible.
This is on the assumption that the specific gravity of the mass C
is the same as that of water ; but as dense earth is about sp. gr. 1-92,
so the actual minimum height of water-rise in the fissure /' will be
1-92 7i.
We have no information as to either the wave-velocity or the angle
of emergence for any locality in this Cachar earthquake. If, how-
ever, we assume the velocity in the vertical component to be 30 feet