A Comparison of Peak Electric Fields and GICs in the Pacific Northwest Using 1-D and 3-D Conductivity Academic Article uri icon


  • AbstractGeomagnetically induced currents (GICs) are a result of the changing magnetic fields during a geomagnetic disturbance interacting with the deep conductivity structures of the Earth. When assessing GIC hazard, it is a common practice to use layercake or onedimensional conductivity models to approximate deep Earth conductivity. In this paper, we calculate the electric field and estimate GICs induced in the long lines of a realistic system model of the Pacific Northwest, using the traditional 1D models, as well as 3D models represented by Earthscope's Electromagnetic transfer functions. The results show that the peak electric field during a given event has considerable variation across the analysis region in the Pacific Northwest, but the 1D physiographic approximations may accurately represent the average response of an area, although corrections are needed. Rotations caused by real deep Earth conductivity structures greatly affect the direction of the induced electric field. This effect may be just as, or more, important than peak intensity when estimating GICs induced in long bulk power system lines.

published proceedings


altmetric score

  • 4.25

author list (cited authors)

  • Gannon, J. L., Birchfield, A. B., Shetye, K. S., & Overbye, T. J.

citation count

  • 21

complete list of authors

  • Gannon, JL||Birchfield, AB||Shetye, KS||Overbye, TJ

publication date

  • November 2017