The Gassmann Equation is a mathematical formula used in geophysics to relate the elastic properties of a saturated rock to its dry state. It helps in understanding how fluids within the rock, such as oil or water, affect its seismic response. This equation is particularly useful in the field of petrophysics for interpreting seismic data and assessing subsurface resources. By applying the Gassmann Equation, geoscientists can estimate the bulk modulus of a rock when it is saturated with different fluids. This allows for better predictions of how the rock will behave under various conditions, aiding in the exploration of hydrocarbon reservoirs and improving the accuracy of geological models.