Physical Oceanography, Vol.
AMPLITUDE-ENERGY CHARACTERISTICS OF TSUNAMI WAVES FOR
VARIOUS TYPES OF SEISMIC SOURCES GENERATING THEM
A. S. Velichko, S. F. Dotsenko, and É. N. Potetyunko
We perform a comparative analysis of the amplitude-energy characteristics of tsunami waves
caused by seismic sources of four types. For the description of tsunami waves, we use linear
equations of long waves. The deformations of the bottom of the ocean are found from the solu-
tion of a problem of elasticity theory for a half space regarded as a model of the lithosphere. The
investigation is based on the analytic solutions obtained by the method of integral transforma-
Seaquakes are one of the main energy sources of tsunami generation . To predict the height of tsunami
waves along the coast, it is necessary to know the parameters of disturbance of the ocean in the zone of a seismic
event. The intensity and space characteristics of hydrodynamic fields at the center of tsunami depend on the
intensity and space-time characteristics of the seismic source . Among various approaches to the investigation
of tsunami and evaluation of the level of tsunami hazard to the coast, there are two models used especially exten-
sively. According to the first model, the motions of the bottom are regarded as given.
The second model (known
as gravitational elastic) studies the process of generation of tsunami waves in the lithosphere–ocean system.
The first approach is reduced to the solution of a hydrodynamic problem of gravity waves generated on the
surface of a layer of water by seismotectonic displacements of the bottom of a basin (see, e.g., [3–5]). As par-
ameters of the generator, one can use approximate empirical dependences of the horizontal scales of the defor-
mation zone and vertical displacements of the bottom on the magnitude of a seaquake [3, 6]. In this case, the de-
pendence of displacements of the bottom of the basin on the parameters of the seismic source and, hence, the re-
lationship between the elements of a tsunami wave and the characteristics of a discontinuity of the earth crust re-
main, to a significant extent, unclear. The relative simplicity and clarity of this model enable us to study the
general properties of the space structure of gravity waves and their amplitude and energy characteristics on the
surface of the ocean.
The gravitational elastic model gives a possibility to simulate the processes of generation of tsunami waves
with more adequate reflection of the characteristics of actual seismic events [7–9]. Within the framework of this
approach, it is assumed that a layer of liquid (ocean) is located over an elastic half space (lithosphere) containing
a seismic source. The general problem is decomposed into two independent problems. In the first problem, it is
necessary to determine the field of displacements in the elastic half space for a given source. The second prob-
lem describes the process of excitation of waves in the ocean by given displacements of the bottom whose form
is determined from the solution of the problem of the theory of elasticity.
The gravitational elastic model is extensively used for reproducing historical tsunami waves and predicting
potentially possible tsunamis in actual oceanic basins [9–11]. With the help of this model, one can determine the
parameters of seismic sources more precisely by comparing the results of numerical calculations with the data on
the climb of actual tsunami waves at the coast .
Rostov State University, Rostov-on-Don, Russia;
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
lated from Morskoi Gidrofizicheskii Zhurnal, No.
12–26, November–December, 2002. Original article submitted June 7, 2001.
308 0928-5105/02/1206–0308 $27.00 © 2002 Plenum Publishing Corporation