The Use of Passive Magnetic Methods in Inferring the Variability of Sub-Glacial Water Systems

Over the past few decades, glaciers worldwide have been retreating, resulting in changes in water resources with direct socio-environmental impacts. The flow of glaciers is intrinsically linked to the morphology and dynamics of sub-glacial water. However, these sub-glacial processes remain largely mysterious, and current techniques of modeling the glacial flow based on these sub-glacial structures is limited to theoretical models with few direct observations of sub-glacial water. Current techniques of observing sub-glacial water systems, including satellite altimetry, boreholes, and active source geophysics, are limited either spatially or temporally. In this study, we present the plausibility of using passive magnetic methods, including magnetic induction and magneto-tellurics, using natural external magnetic fields to detect sub-glacial water morphology and dynamics. Magnetic induction alone was found useful in detecting the presence of smaller bodies of water, but only the variability of large lake-like bodies of sub-glacial water. Magnetotellurics was proven more useful in detecting the presence of smaller bodies of water. We constructed several forward models using these techniques, and calculations of both novel potential measurements and notes on the limitations of these techniques have been made.