ALBERT

Description: A comparison of results from field stations and a laboratory analogue model shows that the electromagnetic response of the Queen Charlotte Islands region is primarily related to the distribution of land and seawater. Almost all of the induction arrows from the simple land-sea model, both in phase and quadrature, have similar directions to those available from the five field sites over the period range of 4 to 120 minutes. The few arrows which differ in direction are influenced by conductive crustal features, not included in the simple model. In contrast to the excellent agreement in direction, the amplitudes of the coastal induction arrows differ between the model and field results: the model amplitudes are too large at short periods (4 min) and too small at long periods (120 min). Thus a more complex structure is required for the lithosphere and upper asthenosphere for the oceanic and land regions than the uniform layer of the present laboratory model. The effect of deflection of the induced electric currents is observed in the model near all capes and bays along the coastline and is very large near Rose Point at the northeast corner of the islands. Contour plots and three-dimensional views of the magnetic and electric field components clearly demonstrate the difficulty in locating a representative reference station for correcting marine or land magnetic surveys in this type of region. © 1983, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.