[CIG-SEISMO] SPECFEM GLOBE : Saving displacement at arbitrary locationssSSS for Wavefield extrapolation ?

[masson]

Hi all,

I am considering using the SPECFEM GLOBE for computing Green's 
functions, that is I need to record the displacement wavefield following 
an impulse at points lying on an arbitrary surface inside the Earth (see 
the attached .pdf for more details). For now, I plan to keep that 
surface in the mantle but later on I may want to include the ICB. 
Basically I need to record the diplacement vector at say a few millions 
of points that are off the SPECFEM GRID (That is a subset of points 
comming form a grid used by another code that models the wavefield 
locally). Possibly it would also be good to filter/decimate the records 
on the fly (That part can wait though, and I already coded some 
real-time compression schemes I could re-use here). After a quick look 
through the code, I see two way to do this :

1)  Modify the receivers subroutines (so I can input only the global 
cartesian coordinates of the points at which I want the displacement and 
return the displacement records expressd in similar coordinates)

2) Mimmic the Movie_Volume procedures : that is output the displacement 
at the elements containg my target points and do the 
spatialextrapolation afterward.

As it seems like a basic task, before I start coding anything, I want 
to be sure I didn't miss something and something similar isn't already 
there somewhere in the code. Has anyone done something similar that I 
could use as a starting point ? Also are there any future plan for using 
the SPECFEM CODE in that fashion ? If this is the case, I would be happy 
to hear about this.

Thank you for your time,

With kind regards,

Yder MASSON

IPGP, Paris, France

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