Does the Earth's magnetic field affect human health?

Not directly. High-altitude pilots and astronauts can experience higher levels of radiation during magnetic storms, but the hazard is due to the radiation, not the magnetic field itself. Direct effects on human health from the magnetic field at the Earth's surface are insignificant. Geomagnetism can impact the electrically-based technology that we rely on, but it does not impact people themselves.

Learn more: USGS Geomagnetism Program

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Do solar flares or magnetic storms (space weather) cause earthquakes?

Solar flares and magnetic storms belong to a set of phenomena known collectively as "space weather". Technological systems and the activities of modern civilization can be affected by changing space-weather conditions. However, it has never been demonstrated that there is a causal relationship between space weather and earthquakes. Indeed, over...

Why measure the magnetic field at the Earth's surface? Wouldn't satellites be better suited for space-weather studies?

Satellites and ground-based magnetometers are important for making measurements of the Earth’s magnetic field. They are not redundant but are instead complementary. Satellites provide good geographical coverage for data collection. Ground-based magnetometers are much less expensive and much easier to install than satellites. An array of...

What are the hazards of magnetic storms?

Our technology-based infrastructure can be adversely affected by rapid magnetic-field variations. This is especially true during “magnetic storms." Because the ionosphere is heated and distorted during storms, long-range radio communication that relies on sub-ionospheric reflection can be difficult or impossible and global-positioning system (GPS...

What is a magnetic storm?

A magnetic storm is a period of rapid magnetic field variation. It can last from hours to days. Magnetic storms have two basic causes: The Sun sometimes emits a strong surge of solar wind called a coronal mass ejection. This gust of solar wind disturbs the outer part of the Earth's magnetic field, which undergoes a complex oscillation. This...

Are we about to have a magnetic reversal?

Almost certainly not. Since the invention of the magnetometer in the 1830s, the average intensity of the magnetic field at the Earth's surface has decreased by about ten percent. We know from paleomagnetic records that the intensity of the magnetic field decreases by as much as ninety percent at the Earth's surface during a reversal. But those...

How does the Earth's core generate a magnetic field?

The Earth's outer core is in a state of turbulent convection as the result of radioactive heating and chemical differentiation. This sets up a process that is a bit like a naturally occurring electrical generator, where the convective kinetic energy is converted to electrical and magnetic energy. Basically, the motion of the electrically...

Do animals use the magnetic field for orientation?

Yes. There is evidence that some animals, like sea turtles and salmon, have the ability to sense the Earth's magnetic field (although probably not consciously) and to use this sense for navigation.

Do any mass extinctions correlate with magnetic reversals?

No. There is no evidence of a correlation between mass extinctions and magnetic pole reversals. Earth’s magnetic field and its atmosphere protect us from solar radiation. It’s not clear whether a weak magnetic field during a polarity transition would allow enough solar radiation to reach the Earth's surface that it would cause extinctions. But...

Could magnetic reversals be caused by meteorite or comet impacts?

Although extremely unlikely, it might be possible for a reversal of the Earth's magnetic field to be triggered by a meteorite or comet impact, or even for it to be caused by something more "gentle," such as the melting of the polar ice caps. But self-contained dynamic systems like Earth’s dynamo can do this without any outside influence. Reversals...

Is it true that Earth's magnetic field occasionally reverses its polarity?

Yes. We can see evidence of magnetic polarity reversals by examining the geologic record. When lavas or sediments solidify, they often preserve a signature of the ambient magnetic field at the time of deposition. Incredible as it may seem, the magnetic field occasionally flips over! The geomagnetic poles are currently roughly coincident with the...

Are earthquakes associated with variations in the geomagnetic field?

Electromagnetic variations have been observed after earthquakes, but despite decades of work, there is no convincing evidence of electromagnetic precursors to earthquakes. It is worth acknowledging that geophysicists would actually love to demonstrate the reality of such precursors, especially if they could be used for reliably predicting...
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Date published: March 5, 2019

New U.S. Geological Survey Report Assesses Risk of Once-Per-Century Geomagnetic Superstorm to the Northeastern 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.  

Date published: March 8, 2018

New 3D Measurements Improve Understanding of Geomagnetic Storm Hazards

Measurements of the three-dimensional structure of the earth, as opposed to the one-dimensional models typically used, can help scientists more accurately determine which areas of the United States are most vulnerable to blackouts during hazardous geomagnetic storms.

Date published: September 12, 2016

Mapping a Space-Weather Menace to Electric-Power Grids

New strides have been made toward quantifying how geomagnetic storms can interfere with the nation’s electric-power grid systems.  

Date published: May 23, 2006

USGS, NOAA Mark 50 Years of Geomagnetic Research at Corbin, Va.

 

On May 23, 1956, a research center and observatory opened at Corbin, Va. to continuously monitor the Earth's magnetic field. It was charged by Congress "to enhance geomagnetic field studies and monitoring programs in support of scientific, general public, basic and national security needs of the United States."

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Aurora
January 31, 2017

Aurora

The National Aeronautics and Space Administration's VISIONS—VISualizing Ion Outflow via Neutral atom imaging during a Substorm—sounding rocket mission is studying what makes auroras and how they affect Earth’s atmosphere. The VISIONS rocket was launched at night in Poker Flats, Alaska, in February 2013. Credit: Joshua Strang, U.S. Air Force

Giant Sunspot Erupts on October 24, 2014
January 31, 2017

Giant Sunspot Erupts on October 24, 2014

Active Region 12192 on the sun erupted with a strong flare on October 24, 2014, prominent in the bright light of this image captured by NASA's Solar Dynamics Observatory. This image shows extreme ultraviolet light that highlights the hot solar material in the sun's atmosphere. Credit: NASA

Earth from space
November 7, 2016

Earth from space

Earth from space

Aurora or "northern lights" are the result of magnetic storms. Credit: Getty Images
April 13, 2016

Aurora

Aurora or "northern lights" are the result of magnetic storms.

December 16, 2013

Hazards: Geomagnetic Storms

Space weather can have important consequences for our lives, such as interference with radio communication, GPS systems, electric power grids, the operation and orientation of satellites, oil and gas drilling, and even air travel as high altitude pilots and astronauts can be subjected to enhanced levels of radiation. It is also during magnetic storms that beautiful aurora

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Attribution: Geomagnetism
USGS
October 16, 2007

Earth Science Week, Continued: Geomagnetism and the Self-Sustaining Dynamo Called Earth

USGS scientist Duane Champion explains the Earth's geomagnetic qualities and the potential for and possible consequences of a geomagnetic shift.

Chart showing the Earth’s magnetic feild

Chart showing the Earth’s magnetic feild

This is one of five world charts showing the declination, inclination, horizontal intensity, vertical component, and total intensity of the Earth’s magnetic field at mean sea level at the beginning of 2005. The charts are based on the International Geomagnetic Reference Field (IGRF) main model for 2005 and secular change model for 2005-2010. The IGRF is referenced to the

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