Accounting for anisotropy in seismic inversion.

[RobertZetica]

Hi there, is it possible to account for the effect of anisotropy when using the TravelTimeManager "Invert" function?

[halbmy]

No, unfortunately not. The algorithm currently supports only isotropic slowness, but we are aware that this feature is of interest for a wide range of applications.

Anybody with experiences in anisotropic traveltime is highly welcomed to be part of the discussion.
An inversion would then invert for a main slowness and an anisotropy factor using either prior knowledge on the angle or still another parameter distribution.

For a globally known anisotropy, one could just deform the whole geometry (sensor positions and mesh) in such a way that it is stretched with the inverse anisotropy factor. Did anyone try that?

[makeabhishek]

I'm also interested to perform anisotropy tomography and I'll be happy to be part to develop it under the guidance.

[halbmy]

Does anyone have a suitable dataset or a benchmark model?

First step could be to deform the mesh globally using a known anisotropy factor. Second could be to invert also for this factor, then to do this based on subsurface regions.

A general solution (spatially distributed anisotropy) would require changing the C++ core for solving the Eikonal equation (by multiplying the traveltime with a correction factor) but more importantly for deriving the Jacobian with respect to the anisotropy factor. Is there any paper already describing the theory? I know colleagues working on the subject.

[makeabhishek]

I don't have a benchmark data. But I did finite element simulations earlier to generate time traces. It's is transversely isotropic. But I can also generate data for fully anisotropic.

[makeabhishek]

What kind of dataset is needed in that case?

[halbmy]

Of course a benchmark dataset helps, but I am missing a paper with the theory for the implementation.

[makeabhishek]

Here are the papers I found.

1. First-arrival traveltime tomography for anisotropic media using the adjoint-state method
2. "Travel times and ray paths for acoustic and elastic waves in generally anisotropic media."