If the model is modified, assume that the velocity is increased
by 50 percent to the right 2000 meters from the source. Then
when the initial source wave impinges on the impedance a
reflected wave will be generated. This inhomogeneous model is
plotted in Figure 5
and the seismic waves are plotted in
Figure 6.
The strength of the reflected wave is
determined by the reflection coefficient [19].
Given the velocities and densities the reflection coefficient **R** is

The subscript 0 is for the incident medium and the subscript 1 is for the transmitting medium. When the density is a constant this simplifies to

The transmitted energy is **T**, **T = 1 - R**.
If the velocity function increases with depth, the reflection
coefficient is positive; if it decreases, the reflection coefficient
becomes negative. The sign change is physically realized as a
polarity change in the reflected signal
which is observed in Figure 7.

Figure 5: Inhomogeneous One Dimensional Model.

Figure 6: Reflected Waves, Velocity Increased 50 percent.

Figure 7: Reflected Waves, Velocity Decreased, 50 percent.