March 13, 1986 – Blackout: The Great Geomagnetic Storm

On this day in engineering history, a powerful geomagnetic storm paralyzed the Hydro-Québec power grid, leaving 6-million customers without electricity for over nine hours. As the world's largest producer of hydroelectric power, Hydro-Québec provides electricity to the Canadian province of Québec as well as to parts of the northeastern United States.

Although the power outage of March 13, 1986 did not extend beyond the Canadian border, the span of this service failure could have been far greater had it occurred during the peak-demand conditions of the summer or winter months.

Understanding Geomagnetic Storms

Geomagnetic storms are temporary disturbances in the Earth's magnetosphere, an extra-atmospheric zone of charged particles that was discovered by Explorer I in 1958. Earth's magnetic field captures charged particles (protons and electrons) carried by the solar wind, an interplanetary stream of ionized particles that flows from the Sun.

In March 1986, the solar wind brought sunspot-induced auroral electroject currents (AEC) into Earth's magnetosphere at speeds as high as 900 km/s. These large, multi-ampere currents flowed in an oval shape and became centered over Earth's north and south magnetic poles, regions where magnetism is concentrated.

Magnetic Poles and Geomagnetically Induced Currents (GIC)

According to the American Geophysical Union (AGU), the Hydro-Québec power grid is particularly vulnerable to geomagnetic storms because of its proximity to Earth's North Magnetic Pole, which lies off Canada's Ellesmere Island and shifts across the Arctic . The North Magnetic Pole is the point on the Earth's surface where the magnetic field is directed vertically downward. When the solar wind is aligned with this magnetic field, the resulting auroras can be especially intense.

Like many other parts of North America, Québec is rich in igneous rock, a geological formation with high electrical resistivity. When geomagnetic storms occur, the AGU's John G. Kappenman explains, "the high resistance of igneous rock encourages geomagnetically induced currents (GICs) to flow in the power transmission lines situated above the rock." The resulting electrical disturbances can be severe.

The image that accompanies this blog-entry (top left) depicts the auroral zone created by the auroral electroject current (AEC) of March 9, 1986. Auroras appear as brightly-colored "lights" in the Earth's atmosphere, typically in the polar regions. With the Great Geomagnetic Storm of 1986, however, auroras were visible as far south as Texas.

Resources:

http://www.agu.org/sci_soc/eiskappenman.html

http://adsabs.harvard.edu/abs/1987SoPh..109..119G

http://en.wikipedia.org/wiki/Hydro-Qu%C3%A9bec

http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/3-what-is-solar-wind.html

http://physics.fortlewis.edu/Astronomy/astronomy%20today/CHAISSON/GLOSSARY/GLOSS_M.HTM

http://en.wikipedia.org/wiki/North_Magnetic_Pole

http://www.abc.net.au/science/news/space/SpaceRepublish_1003429.htm