Bug in source-to-site configuration for Model-to-Model comparison when the required distances are small. [Investigation]

[g-weatherill]

When considering distances that are small (< 5 km) the distance calculations appear to behave unexpectedly and give extremely large values for some cases, resulting in incorrect spectra. This occurs with the following configuration when the dip is set to 60.

{
    "aspect": "1.5",
    "dip": "60",
    "distance": "1,3,5",
    "magnitude": "6.9,7.4",
    "model": [
        "AkkarBommer2010",
        "ChiouYoungs2008",
        "CauzziFaccioli2008",
        "ZhaoEtAl2006Asc"
    ],
    "plot": "s",
    "stdev": true
}

If the dip is set to 90 then the distances are correctly calculated and the spectra look normal.

This could be potentially a bug in the SMTK code, so investigation needed.