Data requirement

[LUCASLOKE]

Can you provide 'topoxyz.dat' and 'Tongariro_SP_data.dat'?

[craigmillernz]

These are provided in the notebooks as part of

tar_folder = download( "https://storage.googleapis.com/simpeg/miller_et_al_2018.tar.gz") 
tar = tarfile.open(tar_folder, "r:*")
tar.extractall()
tar.close()
datadir ="./miller_et_al_2018/"

Note that these notebooks were written for a much older version of SimPEG. There is a simpeg_0.20 branch where some updates have been made. If you'd like to contribute to finishing those updates, that would be great!