Radio transceiver, standard VHF marine when operating near inland shore, 121.5 MHz AM VHF guard channel capable aircraft band transceiver to contact rescuers and high overflying commercial and military aircraft visible by contrails, an optional amateur radio if a licensed radio amateur, (see Ham Radio) or an AM/FM/Weather/Shortwave radio receiver to receive precise time for celestial navigation as well as weather information
The Garmin High Sensitivity GPS tool is a potentially game changing piece of survival gear that employs a quad-helix antenna and GLONASS receiver to provide actionable GPS data even when you’re in the gnarliest locales. With its comprehensive selection of pre-loaded US topographical reference maps you’ll be able to plot an effective escape route from even the direst situations.
I'm not quite crazy enough to say that epinephrine will help you survive the inevitable zombie apocalypse (you can go here for that). I'm just suggesting in a roundabout way that if you happened to be in a situation where something was trying to eat you, the increased heart rate and blood flow to your muscles brought on by a well-timed dose might just save your life.
Earthquakes, tornadoes, and hurricanes can cause you to leave your home or even be trapped there. Roads could be blocked due to fallen trees, power lines, or even damaged earth from the natural disaster. Rescue crews can not be in all places at once. You may have to wait it out for quite a while before its over. You won't be able to go to the store or to the corner market.