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SPECFEM / specfem2d

SPECFEM2D simulates forward and adjoint seismic wave propagation in two-dimensional acoustic, (an)elastic, poroelastic or coupled acoustic-(an)elastic-poroelastic media, with Convolution PML absorbing conditions.
GNU General Public License v3.0
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Using a tomography file with an external mesh #1142

Open firstkingofrome opened 2 years ago

firstkingofrome commented 2 years ago

Hello, I have built a mesh with three materials, I am assigning the bottom two materials statically in my parameter file and would like to use a tomography file to assign material in the top layer. The comments in the default parameter file make it sound like I simply can simply do the following:

1 -1 0 0 ice_tomo.xyz 0 0 0 0 0 0 0 0 0 0

ocean

2 1 1000.d0 1500.d0 0.0d0 0 0 9999 9999 0 0 0 0 0 0

land

3 1 3000.d0 3400.d0 1800.0d0 0 0 600.43763536114344 500.43763536114344 0 0 0 0 0 0

However this resaults in the mesher crashing with the error: error reading material parameters line

I know that the mesh itself is good because if I assign the top layer staticaly (i.e):

1 1 2000.d0 2400.d0 1200.0d0 0 0 136.43763536114344 136.43763536114344 0 0 0 0 0 0

ocean

2 1 1000.d0 1500.d0 0.0d0 0 0 9999 9999 0 0 0 0 0 0

land

3 1 3000.d0 3400.d0 1800.0d0 0 0 600.43763536114344 500.43763536114344 0 0 0 0 0 0

The model works works correctly. Can anyone advise me on the correct syntax to use a tomography file here? I have attached zip archive containing a copy of my complete input file, a low resolution version of my mesh and the tomo_file I have generated. Thank You, I greatly appreciate any assistance in figuring out how to resolve this issue!

filesForGithubQuestion.zip

firstkingofrome commented 2 years ago

In doing some more research I came across this older issue: https://github.com/geodynamics/specfem2d/issues/1003

and was able to resolve this by changing 1 -1 0 0 ice_tomo.xyz 0 0 0 0 0 0 0 0 0 0

to 1 -1 0 0 0.5 0 0 0 0 0 0 0 0 0 0.

I still would like to know what that is doing, can some one explain to my why setting this parameter to 0.5 works? I provide density, vp vs and attenuation in my tomography file so it should not need to use a poissons ratio to compute anything.

Thank You!