Effective magnetic susceptibility of the oceanic upper mantle derived from MAGSAT data

Passive ocean-continent boundaries have little magnetic signatures at MAGSAT altitude, ∼400 km, whereas subducting oceanic lithosphere has well defined magnetic anomalies over some of the subduction zones. Based on this observation, and a thermal evolution model of the oceanic lithosphere subducted along the Kuril-Kamchatka trench, we determined an effective magnetic susceptibility of 0.0085 SI for the upper ∼35 km of the oceanic upper mantle.