Another simple geometry is a reflecting point within the earth. A wave incident on the point from any direction reflects waves in all directions. This geometry is particularly important because any model is a superposition of such point scatterers. Figure 16 shows an example.

Figure 16

The curves in Figure 16 include flat spots for the same reasons that some of the curves in figures12 and 13 were straight lines.

The point-scatterer geometry for a point
located at (*x*,*z*) is shown in Figure 17.

Figure 17

The equation for travel time *t* is the sum of the two travel paths

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10/31/1997