On the equatorial virtual pole distribution

Abstract

In this paper, we show that the Virtual Geomagnetic Pole (VGP) distribution used in paleomagnetic studies is only one of the 2D spherical projections of a 3D paleomagnetic directional data set. Therefore, in principle, the VGP distribution does not by itself completely represent the paleomagnetic directional data set. We suggest that it is necessary to include in the analyses another 2D spherical projection of a 3D paleomagnetic directional data set—the Equatorial Virtual Pole (EVP) distribution. The EVP is defined as the point 90° from the VGP along the great circle through the VGP and the site. The VGP and EVP distributions represent different aspects of the directional data sets and information not carried in the VGP distribution is carried by the EVP distribution. Ideal VGP and EVP distributions depict different aspects of the characteristics of the geomagnetic field as such that, while the VGPs tend to distribute symmetrically around the regions where the field is perpendicular to the earth’s surface, the EVPs concentrate about the nodal or null flux lines.