If you're prepared for zombies, You're prepared for anything!
Colorado Zombie Outpost
For those who don't know, EMP is an acronym for ElectroMagnetic Pulse. It is a wave of electromagnetic energy so powerful that it can "fry" any non shielded electrical or electronic device. EMP's are the result of solar flares, atomic bombs, etc. basically anything that discharges large amounts of electromagnetic energy can create an EMP. The most common source is, of course, solar flares. Recently, minor flares caused disruptions in satellite and cell phone communications over a period of a few weeks. A large solar flare could take down the entire power grid for an indefinite amount of time, affecting all other utilities. Emergency backup systems are only designed to operate for a short amount of time. Eventually they will fail too and without electricity, water and gas plants would eventually cease to pump, meaning no running water, no cooking, and no working toilets. Massive civil unrest, including looting and rioting would soon follow. Eventually the government will, most likely, get things "under control" through the use of National Guard units and Marshal Law, but while the government works to restore power and the National Guard works to restore order, the only person working to help you... will be you.