Geoscience Reference
In-Depth Information
10,000
1,000
0.97 mm
0.51 mm
0.40 mm
0.30 mm
0.22 mm
Fig. 7.19 Turbulent exchange coefficient
K
(7) close to the surface versus acceleration amplitude
of bottom oscillations at various oscillation amplitudes (indicated in figure)
the data considered point to the possibility of significant transformation of the strati-
fication structure in the case of an underwater earthquake. Besides, a most important
feature of the dynamic behaviour of the system considered must be recognized to
be the existence of a sole external parameter—the bottom acceleration amplitude,
which determines the character of this behaviour within a broad range of heights of
the column of liquid. This fact opens the possibility of applying the obtained results
in studies of the seaquake mechanism.
A logical development of the construction of the experimental set-up consisted
in it being equipped with a basin with transparent lateral walls, permitting to ob-
serve the processes taking place in the column of liquid subjected to the influence
of the oscillating bottom. The modified experimental set-up (Fig. 7.20) represented
a rectangular basin with internal dimensions 0
.
22
0
.
22 m. The transpar-
ent lateral walls of the basin were made of plexiglas 30 mm thick, which excluded
the possibility of their vibrating. At the centre of the basin there was a circular
opening, in which there was a piston 0.07 m in diameter, that underwent vertical
harmonic oscillations of given amplitude and frequency. Experiments were carried
out within the following ranges of oscillation amplitudes and frequencies: 5-35 Hz
and 0.6-2.65 mm, respectively.
The basin was continuously filled with stratified liquid (a water solution of NaCl)
exhibiting a vertical density distribution close to linear. The density gradient in dif-
ferent experiments varied between 30 and 500 kg m
−
4
. The water depth in the basin
×
0
.
22
×
