[ghsc-seminars] GHSC Seminar - Jeff Love - 10am, THIS MORNING, Thursday August 19, 2021

[Rigler, Erin (Josh)]

Down to Earth with nuclear electromagnetic pulse (EMP)

Jeff Love, USGS

10am, Thursday August 19, 2021

A nuclear explosion in the near-Earth space environment can produce an electromagnetic pulse (EMP) at the Earth's surface. A low-frequency part of the EMP signal,  known as E3 and covering periods from about a tenth of a second to a few hundred seconds, can induce geoelectric fields in the conducting solid Earth, interfering with the operation of electricity power grids. To investigate this, accurate estimates are required of the Earth's surface impedance - that is, the relationship between geomagnetic and geoelectric field variation. Surface impedance is a function of the electrical conductivity of subsurface rock structures. Using impedance tensors obtained from survey measurements, time-dependent scenario maps are constructed of the E3 geoelectric fields and power-grid geovoltages that would be generated by a hypothetical nuclear explosion above the United States. Over the course of the scenario, geoelectric amplitude, polarization, and variational phase are shown to differ significantly from one location to another, mostly as the result of geographic granularity in impedance. It is concluded that extremely simple impedance models, such as those widely used in government and industry reports concerned with power-grid vulnerability assessment, do not provide accurate estimates of the E3 geoelectric hazard in complex geological settings.

Also, see the following links:

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2021EA001792

https://www.usgs.gov/news/down-earth-complexities-geology-affect-nuclear-electromagnetic-pulse-hazard

https://spaceweatherarchive.com/2021/07/29/nuclear-bombs-can-cause-geomagnetic-storms/


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