An estimate of the conductivity structure for the Vancouver Island region from geomagnetic results

Abstract

The depth to the highly conductive layer of the mantle below the Vancouver Island region is estimated using the results from a scaled laboratory analogue model, a two-dimensional numerical model and field observations. At the centre of the island the responses of numerical models with depths to the mantle of 40 and 80 km bracket the field results. The subduction regime in the Vancouver Island region suggests a dipping interface for the conducting layer. The numerical model based on this type of tectonic structure has a conducting layer within the mantle that varies in depth from 40 km at the continental margin, increasing under the island to 80 km at the shallow channel and decreasing again to 40 km near the mainland coast. The response of this model is compatible with the field observations.