here’s a few tidbits about how the Navy sees a real threat—
http://www.navytimes.com/news/2010/03/navy_emp_032710w/
http://nextnavy.com/emp-threat-analysis-returns/
http://www.navsea.navy.mil/nswc/dahlgren/NEWS/EMP/EMP.aspx
http://www.chips.navy.mil/archives/10_jan/web_pages/Navy_EMP.html
HEre’s a fun read: http://www.rightweb.irc-online.org/articles/display/the_emp_threat_lots_of_hype_little_traction
here’s a peer reviewed paper: http://arxiv.org/ftp/physics/papers/0307/0307127.pdf
Enjoy
Lots of links. But the one I am interested in is your reference to the Hawaii power grid being knocked out.