An excellent idea for a post. Never thought of it. Very practical. Don't know why, exactly, you are prepping but there are some trends in geophysics and solar energy that have my attention, namely: there is going to be a shift in the magnetic poles with a coinciding solar minimum. These two things together can create powerful earthquakes and weather patterns. I suggest you look at SuspiciousObservers on YouTube. Especially the post from 2/11 on this subject. Many blessings.