[CIG-SEISMO] why rotating tensor in model_aniso_mantle.f90 in specfem3D_globe

[Qinya Liu]

Hi Zhitu,

I took a quick look at the subroutine. It seems that the model that
has been implemented is the  (Montagner, 2002) model modified by Min
Chen. I am not entire sure how this model was parameterized and
presented, but my guess is dij is the local elastic tensor, which can
be constructed from the model input files. Then a rotation is applied
to transform it into the global coordinate system: x1=(0 lat 0 lon),
x2=(0 lat, 90 lon), x3=north pole, as most of the calculations in SEM
are done in the global coordinates.

Hope this helps & Good luck,
Qinya

On Wed, Sep 14, 2016 at 3:51 AM, Zhitu Ma <zhitu_ma at brown.edu> wrote:
> Hi, I am trying to benchmark some calculations using an anisotropy model. In model_aniso_mantle.f90, subroutine model_aniso_mantle, the code first calls build_cij to obtain d_ij and then calls rotate_aniso_tensor to obtain c_ij.
>
> I am wondering what the differences are between d_ij and c_ij.  And the rotation depends on lat/long. I am not sure why this is true because d_ij seems to be constructed from local Gc, Gs etc, which have been rotated to east, north, up already?
>
> Thanks,
> Zhitu Ma
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