EM Sounding of Oceanic Upper Mantle in BEMPEX Area (42N, 162W)
24 October 1988
During experiment BEMPEX (Barotropic ElectroMagnetic and Pressure EXperiment, June 1986 - June 1987) 6 simultaneous 2 components horizontal electric and 6 three components magnetic records were obtained covering the entire duration of the deployment (nearly one year). Both electric and magnetic data are available at 4 sites. We make a preliminary inspection and assessment of the data in term of their implications with respect to deep EM sounding of the Oceanic Lithosphere and Mantle. Two important features are conspicuous from simple plots namely (1) considerable differences in the distribution of magnetic variation energy with frequency and azimuth, northward variations being much more energetic than eastward and (2) uncorrelated electric signal from oceanic motion overwhelm the lower frequencies, particularly below .005 cph.