Disturbance In The Earths Magnetic Field

This sequence shows the disturbance in the Earth's magnetic field that triggered the collapse and blackout of the Hydro Quebec system during the Great Geomagnetic Storm of March 13, 1989. Storm conditions (as measured by rapid rates of change in the Earth's magnetic field) are depicted over the time 7:40-8:00 GMT (UT). The Hydro Quebec system blackout occurred at 7:45 GMT. Space Weather conditions capable of threatening power system reliability can evolve rapidly. The system operators at Hydro Quebec and other power system operators across North America faced such conditions during the March 13, 1989 super storm. The animation depicts the rapid development and movement of a large geomagnetic field disturbance between the times 7:42-7:48 UT (2:42-2:48 EST) on March 13, 1989. The disturbance of the magnetic field began intensifying over eastern US-Canada border and then rapidly intensified while moving to the west across North America over the span of a few minutes. From calm conditions, the Hydro Quebec system collapse took an elapsed time of just 90 seconds to occur during this storm. Without better-forecast warnings, sudden and violent storm events provide essentially no time for meaningful human intervention. The most intense portion of this storm surge was actually centered over lower Manitoba and northern Minnesota, where a disturbance magnitude of 865nT/min was observed. This was more than twice the magnitude of the disturbance observed over the Quebec region, which caused the Quebec power grid blackout. The magnetic field disturbances observed at the ground are caused by large electrical currents (electrojet currents) located in the ionosphere at 100 km in altitude that interact with the Earth's magnetic field. The electrojet currents act much like the high altitude wind patterns associated with the jet stream that create ordinary or terrestrial weather patterns; only with Space Weather, the speed and size of these weather patterns can develop extremely fast and on a planetary scale. The large Ionospheric (electrojet) currents that created these magnetic field disturbances, as shown in this animation, moved from eastern Canada to Alaska in less than 8 minutes, a velocity exceeding 1000 km/min.