Geomagnetism

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We monitor the Earth's magnetic field. Using ground-based observatories, we provide continuous records of magnetic field variations; disseminate magnetic data to various governmental, academic, and private institutions; and conduct research into the nature of geomagnetic variations for purposes of scientific understanding and hazard mitigation.

Keeping the Lights On in North America

Keeping the Lights On in North America

Realtime geoelectric maps during a magnetic storm can assist utility companies with their operations and can help power-grid managers to make decisions that may minimize the impact to their systems.

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Risk of Once-Per-Century Geomagnetic Superstorm in NE United States

Risk of Once-Per-Century Geomagnetic Superstorm in NE United States

A new report and map published by the U.S. Geological Survey provides critical insight to electric power grid operators across the northeastern United States in the event of a once-per-century magnetic superstorm.  

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Auroras and Earthquakes: Strange Companions

Auroras and Earthquakes: Strange Companions

In a win-win situation for both seismologists and space physicists, a cheap magnetometer at a seismic station can result in better seismic data for earthquakes and also more geomagnetic data in real time for monitoring space weather.

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News

Date published: September 10, 2021

USGS Hazards Science – Be Informed and Be Prepared

Read below to learn about USGS hazards science, National Preparedness Month, and resources available to explore various hazards in more detail or sign up for alerts.

Date published: July 22, 2021

Down to Earth: Complexities of Geology Affect Nuclear Electromagnetic Pulse Hazard 

Geoelectric hazards generated by a nuclear explosion at the outer edge of Earth’s atmosphere can be strongly affected by the electrical conductivity of rock structures beneath the Earth's surface, according to a study led by the U.S. Geological Survey.  

Publications

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Year Published: 2021

Magnetotelluric sampling and geoelectric hazard estimation: Are national-scale surveys sufficient?

At present, the most reliable information for inferring storm-time ground electric fields along electrical transmission lines comes from coarsely sampled, national-scale magnetotelluric (MT) data sets, such as that provided by the EarthScope USArray program. An underlying assumption in the use of such data is that they adequately sample the...

Murphy, Benjamin Scott; Lucas, Greg M.; Love, Jeffrey J.; Kelbert, Anna; Bedrosian, Paul A.; Rigler, E. Joshua

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Year Published: 2021

Geomagnetic monitoring in the mid-Atlantic United States

Near historic battlegrounds of the American Civil War, southeast of Fredericksburg, Virginia, on a secluded grassy glade surrounded by forest, a specially designed observatory records the Earth’s changing magnetic field. This facility, the Fredericksburg Magnetic Observatory, is 1 of 14 observatories the U.S. Geological Survey Geomagnetism Program...

Love, Jeffrey J.; Lewis, Kristen A.
Love, J.J., and Lewis, K.A., 2021, Geomagnetic monitoring in the mid-Atlantic United States: U.S. Geological Survey Fact Sheet 2021-3001, 2 p., https://doi.org/10.3133/fs20213001.

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Year Published: 2021

Electrical conductivity of the lithosphere-asthenosphere system

Electromagnetic geophysical methods image the electrical conductivity of the subsurface. Electrical conductivity is an intrinsic material property that is sensitive to temperature, composition, porosity, volatile and/or melt content, and other physical properties relevant to the solid Earth. Therefore, imaging the electrical structure of...

Naif, Samer; Selway, Kate; Murphy, Benjamin Scott; Egbert, Gary D.; Pommier, Anne