Finer dicretization of depth search using SPECFEM generated GFs

[ammcpherson]

Hello,

When using SPECFEM generated Green's functions, the directory structure for a depth search requires that each depth much be an integer. I propose that we change the SPECFEM SAC reader to allow at least tenths of kilometers for a depth search.

Thank you, Amanda McPherson

[carltape]

Thanks, Amanda. We definitely want to have the ability to search by 0.1 km depth, such as for shallow explosion events.

[rmodrak]

The following seems relevant, not sure if it's recently been tested though

https://github.com/mtuqorg/mtuq/blob/80a3135c97922dbe8e79023d0564eabaf28f3fce/mtuq/io/clients/SPECFEM3D_SAC.py#L120