The entire answer would be hard ... but depends on the longevity/intensity of the storm. The 1921 event is said to have lasted for over 24 hours (May 13-15). I'

The entire answer would be hard ... but depends on the longevity/intensity of the storm. The 1921 event is said to have lasted for over 24 hours (May 13-15). I'd guess that some effects would be 'spread' to an extent by the magnetosphere. [0] According to WP the "plasma cloud ... compresses the Earth's magnetic field and thus increases this field at the Earth's surface."[1] I'd guess again that this is probably less of a problem away from the area directly struck by the plasma ... for radar, say ... but radio/sat nav effects might be worldwide. Some SWPC details:'Space Weather Scales': [2] It'd be very interesting to see this question addressed in some detail. [0] https://www.youtube.com/watch?v=mEqE-g128kk https://www.youtube.com/watch?v=mEqE-g128kk [1] https://en.wikipedia.org/wiki/Geomagnetic_storm https://en.wikipedia.org/wiki/Geomagnetic_storm [2] http://www.swpc.noaa.gov/sites/default/files/images/NOAAscales.pdf http://www.swpc.noaa.gov/sites/default/files/images/NOAAscal...