Geophysical Mapping: Problem Details 25 of 39 Problem Name: Permafrost and ice detection Problem Type: Natural Hazards Assigned Methods: + Borehole imaging, Structure logging Borehole Methods + DC geoelectrics - Sounding Electrical Methods + Electrical and induction logging Borehole Methods + Frequency-domain electromagnetics - Profiling Electromagnetic Methods + Frequency-domain electromagnetics - Sounding Electromagnetic Methods + Geoelectrics - Tomography (surface based) Electrical Methods + Ground penetrating radar (surface-based) Electromagnetic Methods + Ground penetrating radar - Borehole tomography Electromagnetic Methods + Refraction seismic tomography (surface-based) Seismic Techniques + Seismic crosshole tomography Seismic Techniques + Standard refraction seismics Seismic Techniques + Technical logging Borehole Methods + Time-domain electromagnetics - Profiling Electromagnetic Methods + Time-domain electromagnetics - Sounding Electromagnetic Methods 0 Acoustic logging Borehole Methods 0 DC geoelectrics - Profiling Electrical Methods 0 Geoelectrics - Crosshole tomography Electrical Methods 0 Micro gravity Gravity 0 Nuclear logging Borehole Methods 0 Shallow reflection seismics Seismic Techniques 0 VLF / VLF-R, Radiomagnetotellurics Electromagnetic Methods 0 Vertical seismic profiling (VSP) Seismic Techniques 0 Very-high resolution reflection seismics Seismic Techniques    '+' = Technique applicable; '0' = Application possible/limited use