The formula for the volume of a pyramid is V = (1/3) * A_base * height, where A_base is the area of the base.
For a square base, the area is calculated as side length squared, so the area of the base is 8.7^2 = 75.69 cm^2.
Now plug in the values into the formula:
V = (1/3) * 75.69 * 13.1
V = 327.839 cm^3
Therefore, the volume of the pyramid is approximately 327.8 cubic centimeters.