Such phenomenon can disrupt power grids, radio transmissions and other electronics, and in a worst-case scenario could actually take such systems down, perhaps for extended periods.
Officials with the federal agency said the flare is near the center of the sun and happened at 1:45 EDT Wednesday.
“Impacts to [high frequency] radio communications on the daylight side of Earth lasted for a little more than an hour. … Initial information suggests that [coronal mass ejection] is likely associated with this event, however, further analysis is underway at this time.”
Read more at http://www.wnd.com/2014/09/a-giant-magne...FmpyypR.99
It depends on the intensity, but an EMP could cause a catastrophic, breakdown of power grids and satellites that could last months, or even years.