[CIG-SEISMO] single force solution
Dimitri Komatitsch
komatitsch at lma.cnrs-mrs.fr
Wed Apr 12 07:45:09 PDT 2017
Hi Sevan, Hi all,
This is very good news, it will be very interesting.
I think Jessica Irving was also working on this with a student at
Princeton but I am not sure how far they went (and I do not know if it
was with SPECFEM; for sure they have not committed changes to SPECFEM).
Are you based in Paris or in Berkeley? If you are in Paris we could meet
at ENS on May 10 if you want to discuss that (it would be easier with a
pen and paper + white board :-) , I will be in Paris for a meeting and
would have time to stop by.
Thanks,
Best wishes,
Dimitri.
On 04/12/2017 03:26 PM, Sevan Adourian wrote:
> Hi Dimitri,
>
> Thanks for your answer! Yes, I'm continuing Yder's work on box
> tomography, and I'm trying to allow the stations to be outside of the
> box (which is why I need to compute the Green's functions from an
> "outside" receiver to each point of the mirror for a later convolution
> with the wavefield). In my case I need to couple SPECFEM with a slightly
> modified RegSEM.
>
> But reading what you describe, the problem might still come from me
> because the issues I'm facing are on the SPECFEM side only. So if you
> tell me it already worked, I might still do something wrong.
>
> Regards,
> Sévan
>
> On Wed, Apr 12, 2017 at 3:10 PM, Dimitri Komatitsch
> <komatitsch at lma.cnrs-mrs.fr <mailto:komatitsch at lma.cnrs-mrs.fr>> wrote:
>
>
> Hi Sevan,
>
> Yes, in earlier work
> (http://komatitsch.free.fr/preprints/GJI2_Vadim_2015.pdf
> <http://komatitsch.free.fr/preprints/GJI2_Vadim_2015.pdf> and
> http://komatitsch.free.fr/preprints/Geology_Chevrot_2016.pdf
> <http://komatitsch.free.fr/preprints/Geology_Chevrot_2016.pdf>) we
> have coupled SPECFEM3D with DSM and that worked fine, however more
> recently we have tried to couple SPECFEM3D with AxiSEM to do FWI
> locally with our wavefield injection technique (also similar to e.g.
> Masson and Romanowicz's box tomography approach) and so far we get
> some weird extra phases, possibly something we are doing wrong in
> some rotations. Not sure if the problem is the same as yours, it
> could also be a small mistake we made in the representation theorem
> coupling integral or something like that.
>
> Since you are at Berkeley, is this related to what Yder was doing?
> (I think he was using finite differences, not SPECFEM?).
>
> Thanks,
> Best wishes,
>
> Dimitri.
>
> On 04/12/2017 03:01 PM, Sevan Adourian wrote:
>
> Hi Hom Nath and Dimitri,
>
> Alright then, I'll be waiting for the tests of your new version
> then!
> Dimitri, may I ask you which problems you have faced in the Green's
> functions computation you mentioned earlier? Do you also have one
> component that is satisfying reciprocity? I'm asking because I'm
> trying
> to couple specfem with another external code as well.
>
> Thanks and regards,
> Sévan
>
> On Wed, Apr 12, 2017 at 1:51 PM, Hom Nath Gharti
> <hgharti at princeton.edu <mailto:hgharti at princeton.edu>
> <mailto:hgharti at princeton.edu <mailto:hgharti at princeton.edu>>>
> wrote:
>
> Hi Sévan,
>
> New implementation is very similar, but the source time function
> will have several options. I make it more general because some
> people were interested on a moving source with sine source time
> function, for exampme.
>
> Best,
> Hom Nath
>
>
> On Wed, Apr 12, 2017, 7:36 AM Sevan Adourian
> <sevan.adourian at berkeley.edu
> <mailto:sevan.adourian at berkeley.edu>
> <mailto:sevan.adourian at berkeley.edu
> <mailto:sevan.adourian at berkeley.edu>>>
> wrote:
>
> Hi Hom Nath and Dimitri,
>
> Thank you Dimitri and Hom Nath for the feedback. Hom
> Nath, will
> your new implementation be on the model of what's done in
> specfem Cartesian (i.e. with the FORCESOLUTION file),
> and will
> it support a source that is not on a node of an element
> without
> relocating this source? And will it still use a ricker as a
> source time function?
>
> Thanks,
> Sévan
>
>
> On Wed, Apr 12, 2017 at 1:24 PM, Hom Nath Gharti
> <hgharti at princeton.edu <mailto:hgharti at princeton.edu>
> <mailto:hgharti at princeton.edu <mailto:hgharti at princeton.edu>>>
> wrote:
>
> Hi Dimitri,
>
> I will commit!
>
> Best,
> Hom Nath
>
> On Wed, Apr 12, 2017, 7:09 AM Dimitri Komatitsch
> <komatitsch at lma.cnrs-mrs.fr
> <mailto:komatitsch at lma.cnrs-mrs.fr>
> <mailto:komatitsch at lma.cnrs-mrs.fr
> <mailto:komatitsch at lma.cnrs-mrs.fr>>> wrote:
>
>
> Hi Hom Nath,
>
> Perfect, thanks!
> Then please remember to commit it to GitHub.
>
> Best regards,
> Dimitri.
>
> On 04/12/2017 01:06 PM, Hom Nath Gharti wrote:
> > Hi Sévan,
> >
> > I am about to finish new point force
> implementation. I will let you know
> > once it is ready for testing.
> >
> > Best,
> > Hom Nath
> >
> > On Wed, Apr 12, 2017 at 6:36 AM, Dimitri
> Komatitsch
> > <komatitsch at lma.cnrs-mrs.fr
> <mailto:komatitsch at lma.cnrs-mrs.fr>
> <mailto:komatitsch at lma.cnrs-mrs.fr
> <mailto:komatitsch at lma.cnrs-mrs.fr>>
> <mailto:komatitsch at lma.cnrs-mrs.fr
> <mailto:komatitsch at lma.cnrs-mrs.fr>
>
> <mailto:komatitsch at lma.cnrs-mrs.fr
> <mailto:komatitsch at lma.cnrs-mrs.fr>>>> wrote:
> >
> >
> > Hi Sevan,
> >
> > I guess you can keep cc'ing the list
> because it is an issue Clément,
> > Vadim, Paul, Sébastien and I have been
> facing as well in our coupling
> > with external codes, thus we are
> interested in knowing more about the
> > potential problem.
> >
> > Thanks,
> > Best wishes,
> > Dimitri.
> >
> > On 04/12/2017 11:24 AM, Sevan Adourian wrote:
> > > Hi Hom Nath,
> > >
> > > Thanks for your answer and concern.
> Since you suggest something that is
> > > not directly "specfem related", can I
> send you directly an email so that
> > > we can discuss it? And then I can post
> the solution once we'll find it,
> > > in order to close the topic!
> > >
> > > Thanks again,
> > > Sévan
> > >
> > > On Tue, Apr 11, 2017 at 8:46 PM, Hom
> Nath Gharti <hgharti at princeton.edu
> <mailto:hgharti at princeton.edu> <mailto:hgharti at princeton.edu
> <mailto:hgharti at princeton.edu>>
> <mailto:hgharti at princeton.edu
> <mailto:hgharti at princeton.edu>
> <mailto:hgharti at princeton.edu
> <mailto:hgharti at princeton.edu>>>
> > > <mailto:hgharti at princeton.edu
> <mailto:hgharti at princeton.edu> <mailto:hgharti at princeton.edu
> <mailto:hgharti at princeton.edu>>
> <mailto:hgharti at princeton.edu
> <mailto:hgharti at princeton.edu>
> <mailto:hgharti at princeton.edu
> <mailto:hgharti at princeton.edu>>>>> wrote:
> > >
> > > 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
> <mailto:sevan.adourian at berkeley.edu>
> <mailto:sevan.adourian at berkeley.edu
> <mailto:sevan.adourian at berkeley.edu>>
> > <mailto:sevan.adourian at berkeley.edu
> <mailto:sevan.adourian at berkeley.edu>
> <mailto:sevan.adourian at berkeley.edu
> <mailto:sevan.adourian at berkeley.edu>>>
> > <mailto:sevan.adourian at berkeley.edu
> <mailto:sevan.adourian at berkeley.edu>
> <mailto:sevan.adourian at berkeley.edu
> <mailto:sevan.adourian at berkeley.edu>>
>
> > <mailto:sevan.adourian at berkeley.edu
> <mailto:sevan.adourian at berkeley.edu>
> <mailto:sevan.adourian at berkeley.edu
> <mailto: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
> <mailto:sevan.adourian at ens.fr>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>>>
> > <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>>>>
> > >
> > >
> > >
> > >
> _______________________________________________
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> <mailto:CIG-SEISMO at geodynamics.org>
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> > >
> >
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
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>
> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>>
> >
> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>
>
> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>>>
> > >
> >
> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>
>
> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>>
> >
> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>
>
> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>>>>
> > >
> > >
> > >
> > >
> > > --
> > > Sevan Adourian
> > > Masters Student at Ecole Normale
> Superieure de Paris
> > > sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>>>
> > <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>
> <mailto:sevan.adourian at ens.fr
> <mailto:sevan.adourian at ens.fr>>>>
> > >
> > >
> > >
> _______________________________________________
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> <mailto:CIG-SEISMO at geodynamics.org>>>
> > >
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> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>>
> >
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> > >
> >
> > --
> > Dimitri Komatitsch, CNRS Research Director
> (DR CNRS)
> > Laboratory of Mechanics and Acoustics,
> Marseille, France
> > http://komatitsch.free.fr
> >
> _______________________________________________
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> >
> >
> >
> >
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> >
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> <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo <http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo>>
> >
>
> --
> Dimitri Komatitsch, CNRS Research Director (DR CNRS)
> Laboratory of Mechanics and Acoustics,
> Marseille, France
> http://komatitsch.free.fr
> _______________________________________________
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>
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>
>
>
> --
> Sevan Adourian
> Masters Student at Ecole Normale Superieure de Paris
> sevan.adourian at ens.fr <mailto:sevan.adourian at ens.fr>
> <mailto:sevan.adourian at ens.fr <mailto:sevan.adourian at ens.fr>>
>
>
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>
>
>
> --
> Sevan Adourian
> Masters Student at Ecole Normale Superieure de Paris
> sevan.adourian at ens.fr <mailto:sevan.adourian at ens.fr>
> <mailto:sevan.adourian at ens.fr <mailto:sevan.adourian at ens.fr>>
>
>
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>
> --
> Dimitri Komatitsch, CNRS Research Director (DR CNRS)
> Laboratory of Mechanics and Acoustics, Marseille, France
> http://komatitsch.free.fr
> _______________________________________________
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>
>
>
>
> --
> Sevan Adourian
> Masters Student at Ecole Normale Superieure de Paris
> sevan.adourian at ens.fr <mailto:sevan.adourian at ens.fr>
>
>
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--
Dimitri Komatitsch, CNRS Research Director (DR CNRS)
Laboratory of Mechanics and Acoustics, Marseille, France
http://komatitsch.free.fr
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