When a body waves reaches a distance ‘r’ from it’s source in a homogeneous
medium, the wavefronts (defined as the surface in which all particles vibrate
with the same phase) has a spherical shape and the wave is called aspherical
wave. As the distance from the source increases, the curvature of the spherical
wavefront decreases. At great distances from the source the wavefront is so flat
that it can be considered to be a plane and the seismic wave is called Plane
wave. The direction perpendicular to the wavefront is called the seismic ray
path, The description of harmonic waves in plane waves is simpler than for
spherical waves, because for plane waves we can use arthogonal Cartesian
coordinates. Even for plane waves the mathematical description of the three
dimensional displacements of the medium is fairly complex. However, we can
learn quite a lot about body wave propagation from a simpler, less rigorous
description.
6.0 Tutor Marked Assignment
:
Q 1.
a)
What is Seismic Waves?
b)
State the law of reflection
c)
State the Snell’s law
Q 2.
With the aid of a simple diagram explain and show the following concept
in seismic theory.

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