I study the masters, never their students.— William Rowan Hamilton (1805-1865)
The distinction between intrinsic and apparent frequency-dependent seismic properties is nowhere greater than in the area of attenuation.
If we take a rock sample from a well core and test it in the laboratory at kilohertz to megahertz frequencies, we are likely to find some small amount of intrinsic attenuation, meaning the irrecoverable loss or conversion of wave energy into heat. That experiment will yield the frequency-dependent wave-energy loss as observed, for example, over the length of a 1-inch rock sample. In the frequency band of surface-seismic data, 5 to 100 Hz, the intrinsic attenuation is relatively constant and generally small. Extrapolating that level of intrinsic attenuation to a geologic section several kilometers thick still will predict only a modest loss of wave energy.