[CIG-SEISMO] single force solution

[Hom Nath Gharti]

Hi Sévan,

Do you also switch the orientations of source and receiver?

Thanks,
Hom Nath

On Tue, Apr 11, 2017 at 1:39 PM, Sevan Adourian <sevan.adourian at berkeley.edu
> wrote:

> Hi cig-seismo community,
>
> I'm trying to compute Green's functions using Specfem3D-Globe, using a
> single force point source solution coupled with a source time function that
> basically represents a filtered Dirac delta. In order to test my
> implementation, I imposed a source at a point A and looked at the obtained
> Green's function at a receiver B. Then, I switched the position of the
> source and the receiver and compared the 2 in order to check the
> reciprocity of those Green's functions.
>
> It turned out that I have a perfect reciprocity (in the frequency band
> that correspond to my filtered Dirac delta) only on the component in which
> I input the force, while the other components don't quite match.
>
> I strongly suspected a reference frame rotation issue, so I tried to input
> the force in the global xyz coordinate system (i.e. adding the force
> directly in the accel_crust_mantle array in the comp_add_sources
> subroutine, without multiplying with the nu_source matrix) and looked at
> the Green's functions in this xyz coordinates system (ie, directly writing
> in the seismograms structure the values of ux, uy and uz computed in the
> compute_seismogram subroutine), but I still have this issue. Would anyone
> have an idea of where this probable rotation issue could come from?
>
> I'm working on specfem3D-Globe v6.0.0.
>
> Thanks in advance for your help!
> Sévan
>
> --
> Sevan Adourian
> Masters Student at Ecole Normale Superieure de Paris
> sevan.adourian at ens.fr
>
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