3D velocity model in NonLinLoc for a spherical coordinate system

[DawnChen0717]

Dear Anthony,

How can I use a 3D grid for a spherical coordinate system? The manual only mentions how to implement in a Cartesian coordinate system.

Many thanks,
Dawn

[alomax]

Hello Dawn,

For spherical coordinates use TRANS GLOBAL. Then the x and y, and dx and dy specifications for *GRID and LOCGRID are in degrees. See https://github.com/alomax/NonLinLoc/blob/dev/nlloc_global_sample/run/neic_global.in for some examples control file entries.

To use 3D travel-times, it is best to calculate the 3D travel-times outsize of NLL and transform to the NLL GRID format with the TRANS GLOBAL conventions above to store the travel-times. The grid file names must also follow the NLL conventions:

my_area_3Dttime.P.<NET_STA_CODE>.time.buf
my_area_3Dttime.P.<NET_STA_CODE>.time.hdr

I am sure you need more details, but I start with just the above to be sure I am answering you question correctly.

Best regards,
Anthony