PHY 361 GEOPHYSICS II

# When a body waves reaches a distance r from its

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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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