Emily Jo Graves, University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK, United States, Ronni Grapenthin, University of Alaska Fairbanks, Geophysical Institute, Fairbanks, United States, Alex J Rinehart, New Mexico Institute of Mining and Technology, Earth and Environmental Science, Socorro, NM, United States and Mark Austin Person, New Mexico Tech, Earth & Environmental Science, Socorro, NM, United States