Geomagnetic Storm - Historical Occurrences

Historical Occurrences

Early in the 19th century the first geomagnetic storm was observed, or to be more precise the effects of it were observed: From May 1806 until June 1807 the German Alexander von Humboldt surveyed the bearing of a compass in Berlin. On 21 December 1806 he registered severe disturbances and Aurorae could be seen in that night.

On September 1 – 2, 1859, the largest recorded geomagnetic storm occurred. From August 28 until September 2, 1859, numerous sunspots and solar flares were observed on the Sun, the largest flare occurring on September 1. This is referred to as the 1859 solar superstorm or the Carrington Event. It can be assumed that a massive Coronal mass ejection (CME), associated with the flare, was launched from the Sun and reached the Earth within eighteen hours — a trip that normally takes three to four days. The horizontal intensity of geomagnetic field was reduced by 1600 nT as recorded by the Colaba observatory near Bombay, India. It is estimated that Dst would have been approximately -1750 nT. Telegraph wires in both the United States and Europe experienced induced emf, in some cases even shocking telegraph operators and causing fires. Aurorae were seen as far south as Hawaii, Mexico, Cuba, and Italy — phenomena that are usually only seen near the poles. Ice cores show evidence that events of similar intensity recur at an average rate of approximately once per 500 years. Since 1859, less severe storms have occurred, notably in 1882, 1921 (May 1921 geomagnetic storm), with disruption of telegraph service and inititation of fires, and 1960, when widespread radio disruption was reported.

On March 13, 1989 a severe geomagnetic storm caused the collapse of the Hydro-Québec power grid in a matter of seconds as equipment protection relays tripped in a cascading sequence of events. Six million people were left without power for nine hours, with significant economic loss. The storm even caused aurorae as far south as Texas. The geomagnetic storm causing this event was itself the result of a coronal mass ejection, ejected from the Sun on March 9, 1989. The minimum of Dst was -589 nT.

On July 14, 2000, an X5 class flare erupted on the Sun (known as the Bastille Day event) and a coronal mass ejection was launched directly at the Earth. A geomagnetic super storm occurred on July 15–17; the minimum of the Dst index was – 301 nT. Despite the strength of the geomagnetic storm, no electrical power distribution failures were reported. The Bastille Day event was observed by Voyager 1 and Voyager 2, thus it is the farthest out in the solar system that a solar storm has been observed.

Seventeen major flares erupted on the Sun between 19 October and 5 November 2003, including perhaps the most intense flare ever measured on the GOES XRS sensor – a huge X28 flare, resulting in an extreme radio blackout, on 4 November. These flares were associated with CME events which impacted the Earth. The CMEs caused three geomagnetic storms between Oct 29 and November 2 during which the second and third storms were initiated before the previous storm period had fully recovered. The minimum Dst values were -151, -353 and -383 nT. Another storm in this event period occurred on November 4 – 5 with a minimum Dst of -69.nT. The last geomagnetic storm was weaker than the preceding storms because the active region on the Sun had rotated beyond the meridian where the central portion CME created during the flare event passed to the side of the Earth. The whole sequence of events is known as the ‘Halloween Storm’. The Wide Area Augmentation System (WAAS) operated by the Federal Aviation Administration (FAA) was offline for approximately 30 hours due to the storm. The Japanese ADEOS-2 satellite was severely damaged and the operation of many other satellites were interrupted due to the storm.