I stumbled across some research papers published in 2010 by Oak Ridge about the causes and effects of different types of electromagnetic pulses including solar, nuclear, and non-nuclear emp weapons. It's extremely deep and highly technical but one can scan the documents and summaries to get an idea. It's not at all light reading (and might make for good sleeping materal..yawn....) but is interesting none the less so I thought you guys might like it. Enjoy!
http://web.ornl.gov/sci/ees/etsd/pes/ferc_emp_gic.shtml
http://web.ornl.gov/sci/ees/etsd/pes/ferc_emp_gic.shtml