[CIG-SEISMO] simulation of seismic wave propagation excited by a force

[iqbalj at ujf-grenoble.fr]

Sir,
Point force source in 3D code an option of inclined force like that in  
2D code, is not available. If it is not too complicated to add then  
please also add this option in 3D code.
Thanks
Javed


Quoting Dimitri Komatitsch <komatitsch at lma.cnrs-mrs.fr>:

>
> Hi Christina and Yang, Hi all,
>
> OK, great. This is excellent news.
>
> So let us just move this "USE_FORCE_POINT_SOURCE" flag from
> setup/constants.h.in to DATA/Par_file, and let us mention it in the manual.
>
> Jo, could you please do that and commit the changes?
>
> Thank you,
> Dimitri.
>
> On 09/11/2012 06:17 PM, Christina Morency wrote:
>> Hi Dimitri,
>>
>> Yes, I can confirm what Yang is saying, it is already in the package,
>> with interpolation if the source is not located on a GLL point (as it is
>> indeed done in the 2D btw).
>>
>> Christina
>>
>> On 09/11/2012 09:14 AM, Yang Luo wrote:
>>> I think Daniel (or someone else) has already copied necessary  
>>> lines from old package.
>>>
>>> There is an option "USE_FORCE_POINT_SOURCE" in constant.h, which  
>>> allows one to use a point force
>>> (which Yingzi already figured out, or maybe it's already in the manual)
>>>    logical, parameter :: USE_FORCE_POINT_SOURCE = .false.
>>>    double precision, parameter :: FACTOR_FORCE_SOURCE = 1.d15
>>>    integer, parameter :: COMPONENT_FORCE_SOURCE = 3  ! takes  
>>> direction in comp E/N/Z = 1/2/3
>>>
>>> Interpretation is included, if the point force is not located  
>>> exactly on a GLL point.
>>>
>>>
>>>
>>>
>>>
>>>
>>> ________________________________________
>>> From: Dimitri Komatitsch [komatitsch at lma.cnrs-mrs.fr]
>>> Sent: Tuesday, September 11, 2012 12:01 PM
>>> To: Yingzi Ying
>>> Cc: cig-seismo at geodynamics.org; Joseph Charles; Paul Cristini;  
>>> ???; Yang Luo; Christina Morency
>>> Subject: Re: [CIG-SEISMO] simulation of seismic wave propagation  
>>> excited by a   force
>>>
>>> Dear Yingzi,
>>>
>>> You are right, in the current code there is no option in the Par_file to
>>> use a point source, but we added this to the todo list right before the
>>> summer and thus we should/will definitely do it. It is easy to do: just
>>> add the Ricker wavelet to the accel() vector (which is in fact a force
>>> vector before we divide it by the mass matrix), to the component you
>>> want (vertical or horizontal) and you are all set.
>>>
>>> Joseph, could you maybe do it? below are a few lines from one of my test
>>> codes, in which I do just that; let us cut and paste these lines in
>>> SPECFEM3D (it is just a matter of selecting the right grid point; which
>>> we already do for a CMT source, thus we could add a force instead of a
>>> CMT at that location; the only difference being that the CMT source is
>>> added to all the points of a given spectral element, while a force
>>> vector should be added to a single point).
>>>
>>> Let me talk to Joseph tomorrow to see if we can release a patch of the
>>> source code soon.
>>>
>>> I also cc Yang to see if he has already done that in a local version at
>>> Princeton maybe (for instance to model a force for some of his oil
>>> industry simulations in foothill regions?).
>>>
>>> Another difficulty is if the location of the force does not correspond
>>> to a grid point; then there are two options:
>>>
>>> - select the closest grid point; i.e. slightly change the location of
>>> the source (can be done automatically by the code)
>>>
>>> - use Christina Morency's way of adding a force source between grid
>>> points; I think I remember she did that in the 2D code, but I am not
>>> sure how; thus I cc her.
>>>
>>> (that second option would be better, if Christina can confirm that it
>>> works fine)
>>>
>>> Best wishes,
>>> Dimitri.
>>>
>>> ==================================================================
>>>
>>> ! ipoinsource is the global grid point at which we add the source
>>> ! "3" means a vertical force (i.e. we add the force to the vertical
>>> ! component of the force vector, which is later divided by the mass
>>> ! matrix to get the acceleration vector)
>>> ! factor_force is the norm of the force vector to add
>>> ! ricker(t) is the Ricker wavelet at time t = (it-1)*deltat
>>>
>>>     accel(3,ipoinsource) = accel(3,ipoinsource) - factor_force * ricker(t)
>>>
>>> ==================================================================
>>>
>>> On 09/11/2012 12:59 PM, Yingzi Ying wrote:
>>>> Hi all,
>>>>
>>>> I am trying to use specfem3d to simulate waves excited by a vertical
>>>> force with user-defined source forms such as ricker wavelet.
>>>>
>>>> I tried to do it through adjoint simulation by setting 'SIMULATION_TYPE
>>>> = 2' and put source position at STATIONS_ADJOINT and receivers at
>>>> CMTSOLUTION. But I failed.
>>>>
>>>> Does anyone have an idea or suggestion how to do active simulations with
>>>> specfem3d?
>>>>
>>>> Thanks in advance.
>>>>
>>>> Best regards,
>>>> Yingzi
>>>>
>>>>
>>>> _______________________________________________
>>>> CIG-SEISMO mailing list
>>>> CIG-SEISMO at geodynamics.org
>>>> http://geodynamics.org/cgi-bin/mailman/listinfo/cig-seismo
>>> --
>>> Dimitri Komatitsch - komatitsch aT lma.cnrs-mrs.fr
>>> CNRS Research Director (DR CNRS), Laboratory of Mechanics and Acoustics,
>>> UPR 7051, Marseille, France    http://komatitsch.free.fr
>>
>
> --
> Dimitri Komatitsch - komatitsch aT lma.cnrs-mrs.fr
> CNRS Research Director (DR CNRS), Laboratory of Mechanics and Acoustics,
> UPR 7051, Marseille, France    http://komatitsch.free.fr
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>