Backus showed that layering on a scale much finer than the wavelength has an impact and that a number of isotropic layers can be replaced by a homogeneous transversely isotropic medium that behaves exactly in the same manner as the actual medium under static load in the infinite wavelength limit.
12.
:In an simple isotropic medium it would generally be distance squared, but there is a correction for scattering so it is really more like P \ varpropto { e ^ {-r \ over \ lambda } \ over r ^ 2 }, where & lambda; is about 1 km in the ocean.
