Translations:Useful attenuation mechanisms/33/en

At great enough depths, the presence of random noise generally precludes the possibility of obtaining good-quality seismic acoustic-impedance logs. The random noise level depends on agents such as wind noise (either acting directly on the geophones or indirectly by shaking the ground) and the scattering of horizontally traveling waves by random inhomogeneities. In addition, although transmission through a water layer is excellent, irregularities in the form of bottom scatterers within the water (fish, gas bubbles, or man-made artifacts) combine to give incoherent scattered energy that persists up to high frequencies. Penetration of high-frequency energy directly into the earth and the return of high-frequency energy from the target layers is limited both by irreversible absorption through solid friction and by such purely elastic phenomena as the loss of energy by reverberations and transmission through many layer boundaries.