Inverse kinematic problem for a random gradient medium in geometric optics approximation |
| |
| Authors: | N V Petersen |
| |
| Institution: | (1) Institute of Physics of the Earth, USSR Academy of Sciences, Moscow, USSR |
| |
| Abstract: | Scattering at random inhomogeneities in a gradient medium results in systematic deviations of the rays and travel times of refracted body waves from those corresponding to the deterministic velocity component. The character of the difference depends on the parameters of the deterministic and random velocity component. However, at great distances to the source, independently of the velocity parameters (weakly or strongly inhomogeneous medium), the most probable depth of the ray turning point is smaller than that corresponding to the deterministic velocity component, the most probable travel times also being lower. The relative uncertainty in the deterministic velocity component, derived from the mean travel times using methods developed for laterally homogeneous media (for instance, the Herglotz-Wiechert method), is systematic in character, but does not exceed the contrast of velocity inhomogeneities by magnitude. The gradient of the deterministic velocity component has a significant effect on the travel-time fluctuations. The variance at great distances to the source is mainly controlled by shallow inhomogeneities. The travel-time flucutations are studied only for weakly inhomogeneous media. |
| |
| Keywords: | Scattering random inhomogeneities travel time inversion |
| 本文献已被 SpringerLink 等数据库收录！ |
|
