Geoscience Reference
In-Depth Information
Fig. 2.16 Layout of laboratory set-up for simulating tsunami generation by deformations of
the basin bottom. 1—wave damper (slope), 2—pneumatic wave generator, 3—main line of pres-
sure supply, 4—guiding cylinder, 5—sensor of basin bottom motion, 6—IR wavegraph
Fig. 2.17 Layout of laboratory set-up for simulating tsunami generation by a running displace-
ment. 1, 2, 3—pneumatic wave generators, 4, 5—IR wavegraphs
In conclusion of this section we shall turn to experimental tests of the the-
oretical relationships found between wave parameters and source characteristics.
We shall briefly describe the layout of laboratory experiments. The set-up was
an open rectangular hydrocanal with transparent walls of organic glass of dimen-
sions 0
.
15
3
.
3 m (Fig. 2.16). As the source of waves, imitating vertical
displacements of the basin bottom, use was made of a pneumatic generator rep-
resenting a rectangular volume with rigid upper and lower sides, and elastic lateral
sides. Model displacements of the basin bottom were registered by a sensor, rep-
resenting a fixed inductance coil and a ferrite core, connected to the moving upper
side. Several generators of the same type of dimensions 0
.
3
×
0
.
15
×
0
.
15 m
were used. The inclined plane at the end of the canal served as a wave damper. The
depth of the water varied between 0.04 and 0.1 m.
The described system permitted to simulate not only single piston-like and
membrane-like displacements, but also oscillations of the basin bottom. For simu-
lation of a running displacement use was made of three identical generators, driven
sequentially (Fig. 2.17). The registration of waves on the free water surface was
performed with the aid of optical sensors—IR wavegraphs [Nosov, Shelkovnikov
(1991)]. Unlike traditional contact methods of wave measurements on a water
surface, an IR wavegraph introduces no distortion in the surface at the point of mea-
surement, therefore, it can measure waves of small amplitude (0.1 mm and less).
Measurement of waves of such small amplitudes is essential in physical simula-
tion of tsunamis in the open ocean. Observation of geometrical similarity [Basov
et al. (1984)] requires conservation of the relationship between the wave amplitude
×
0
.
15 and 0
.
7
×
