Observatory geoelectric fields induced in a two-layer lithosphere during magnetic storms

Earth, Planets and Space
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Abstract

We report on the development and validation of an algorithm for estimating geoelectric fields induced in the lithosphere beneath an observatory during a magnetic storm. To accommodate induction in three-dimensional lithospheric electrical conductivity, we analyze a simple nine-parameter model: two horizontal layers, each with uniform electrical conductivity properties given by independent distortion tensors. With Laplace transformation of the induction equations into the complex frequency domain, we obtain a transfer function describing induction of observatory geoelectric fields having frequency-dependent polarization. Upon inverse transformation back to the time domain, the convolution of the corresponding impulse-response function with a geomagnetic time series yields an estimated geoelectric time series. We obtain an optimized set of conductivity parameters using 1-s resolution geomagnetic and geoelectric field data collected at the Kakioka, Japan, observatory for five different intense magnetic storms, including the October 2003 Halloween storm; our estimated geoelectric field accounts for 93% of that measured during the Halloween storm. This work demonstrates the need for detailed modeling of the Earth’s lithospheric conductivity structure and the utility of co-located geomagnetic and geoelectric monitoring.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Observatory geoelectric fields induced in a two-layer lithosphere during magnetic storms
Series title Earth, Planets and Space
DOI 10.1186/s40623-015-0213-3
Volume 67
Year Published 2015
Language English
Contributing office(s) Geologic Hazards Science Center
Description art58: 12 p.
Country Japan
City Kakioka
Online Only (Y/N) N
Additional Online Files (Y/N) N