Seth William Campbell1,2,3| Martin Briggs4| Samuel G. Roy1,5|Thomas A. Douglas6| Stephanie Saari6 1University of Maine, School of Earth and Climate Sciences, Orono, Maine, USA  2 University of Maine, Climate Change Institute, Orono, Maine, USA  3U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire, USA  4 U.S. Geological Survey, Earth System Processes Division, Hydrogeophysics read more Ground-penetrating radar, electromagnetic induction, terrain, and vegetation observations coupled with machine learning to map permafrost distribution at Twelvemile Lake, Alaska – Wiley – S. Campbell et al.