BUT, when it happens, it's going to be too sudden for many of us to survive, no matter what we do to prepare. Well, that is unless you have a spaceship or submarine, fueled-up , provisioned, and ready to go.
Thanks for the heads-up. However, I can't afford a spaceship or a submarine; not even a used one. Nevertheless, I have a plan. Take a torch and cut the end off a thousand-gallon propane fuel tank. But first, be sure that the tank is empty! I can't stress the importance of this enough. Next, line the inside of the tank with a four-inch thick layer of Memory Foam. Then fit the inside of that with inner-tubes that all have the same outer diameter, but with inner diameters that will match the area of your body that it will be protecting. Then put the end back on in a way that will allow you to tighten it down securely from the inside. Of course, any free space will be used to hold as many oxygen tanks as possible.
On the outside, large tractor-tire inner-tubes will slide over the end of the tank from one end to the other. And surrounding all that will be a large canvas tarp. The idea is to make it so secure that nothing short of a giant with a ball-bat the size of a redwood tree could cause enough damage to threaten your life. And be sure to use new inner-tubes; brand name, too. You don't want to cheap out when it comes to this. You also don't want to cheap out on the canvas tarp, either. Like, don't go out behind the old shed and peel that old tarp from the damp and dirty ground, feeling pleased to have finally found a use for it after all these years. For one thing, it's ******* rotted! Don't kid yourself. Buy a new tarp!
And then there's the nagging issue of what to do if something goes wrong and the integrity of your pod is compromised. I can't imagine what could go wrong, though. I suppose maybe a Cruise Missle specifically targeting your pod would do it; or a tall building might tip over and pin your pod underwater; or, just your luck, you find yourself being crushed between an aircraft carrier and a super oil-tanker drifting dead in the sea after that big wave goes through; or you end up adrift in frigid waters with no hope of reaching anywhere before freezing to death. These things are not likely to happen. But if one of them does, you want something that can get you out of trouble in a flash.
And by "out of trouble" I mean "out of this existence" because, let's face it, in a post-apocalyptic scenario of the nature of which you're speaking, you would certainly suffer a horrible death should your pod fail. You would struggle and then drown in a stew of toxins and chemicals of every kind. A shark attack would be more merciful, but unfortunately, the stew will have already killed every last shark.
A bundle of dynamite with a very short fuse should do the trick; a sort of manual version of a cynide suicide pill. The oxygen tanks would blow, too, further ensuring your instant exit from this reality.
And if you wanted, you could have a small, remote camera mounted somewhere on the outside of your pod, but do you really want or need to see a detailed picture of what's going on outside your pod during those intense first hours or days of such a cataclysmic upheaval? I don't think so. My guess is that after your first corpse sighting, you're going to shut that camera off and probably even disable it just to be sure. But the damage will already be done. You can't unsee it; doesn't work that way. The best thing that could possibly come from recording such a thing is that you would definitely win the one hundred thousand dollar prize on Amerca's Funniest Home Videos after the world returns to normal and television is back up and running again. It would be a short clip showing nothing but the faces of the corpses floating by and the sound of you screaming; and of course the faces would be blurred out like they do with baby butts.
So, a pole-shift doesn't necessarily have to be a death sentence. In fact, I'm going to get on the phone and order the things I'll need to survive.