Evaluating the effects of magnetic soils on TEM measurements for UXO detection

The task of discriminating UXO from non-UXO items are more difficult when sensor data are contaminated with geological noise originating from magnetic soils. In particular, magnetic material affects the decay curve characteristics in electromag-netic surveys and this can adversely affect inversion calculations that try to estimate parameters of the UXO or determine whether the item is UXO or scrap. This talk focuses on the effects mag-netic soils and magnetic viscosity have on time domain and fre-quency domain electromagnetic sensor data. By forward mod-elling of a 1-D layered earth model we investigate the sensitivity of surveys to magnetic soils, and attempt to determine the rela-tive strengths of magnetic soils and buried metallic objects. In particular, we consider soil susceptibility models appropriate for Kaho’olawe Island, Hawaii, where the UXO clearance project has been hampered by the presence of highly magnetic basalti