Okay, just for the sake of argument, let's assume that the following condition is true: Three large interstellar objects are going to impact the planet in the next thirty days.
There are a huge number of variables that determine one's likely short-term outlook in such a case.
1. Objects mass, speed and composition- IOW is it a 'dirty snowball' cometary object, which is shedding mass furiously as it approaches the Sun, or a nickel and iron asteroid that will remain largely intact- even through atmospheric entry? What will the energy release numbers look like?
2. Locations of impact. In the ocean? Which ocean, where? What are the characteristics of the imact sites, whether marine or on land? What does the geology look like under them? Per question number one, is there sufficient energy that we end up with a big crater someplace, or is there a chance of severe geologic disturbance up to, in an extreme case, cracking the planetary crust? Does it jostle a subduction zone and cause secondary effects like a massive earthquake or popping open the caldera at Yellowstone?
Right now we have no mass, speed, composition or impact site data. In short, we know nothing.
Let's say it's an ocean impact in the Atlantic, eight hundred miles off of the North American continental shelf, water is two miles deep, object is solid in nature. Impact site is relatively geologically stable. Assuming, and I am just pulling this notion out of the air, that it is a survivable event at any location that either one of us are likely to be, what can we expect?
Large, destructive waves in coastal areas- possibly global in nature. Large, destructive shock wave transmitted through the ground. These could be anything from real monsters that pretty much reduce civilization as we know it to little or nothing, to just chucking peoples yachts into the streets. Depends on the values we plug into question #1.
Seismic disturbances ranging from a temblor that makes people run outside and look around at each other, to bouncing people, buildings and cars into the air. Again, depends on the math.
If I were really determined to survive something like this, I'd move to the Rockies or someplace, pick my homesite with infinite care, have the ability to farm, hunt and fish and protect myself from any possible hordes of the unprepared. Unless a)The impact is of such violence that this is all moot, or b) I get squashed like a bug by having the rotten luck of being at Ground Zero.
Speaking of which, the effect of 9/11 that I found most startling was the disruption in the fabric of American society. There were economic ramifications that were significant. Suppose, in that light, that a GFRFS landing in the Atlantic were to sweep the humanity, economy, infrastructure and institutions on the eastern coast of North America away, and to a lesser extent, the west as well. On 9/11, we lost a few buildings, a few thousand people, and we became aware undeniably, that we are at war. Now multiply that times the number of likely victims and damage from losing the whole east coast.
For some period of time, we wouldn't be a society anymore. You'd be on your own.
A lot of people would die from the primary effects and secondary ones as well. What happenes to the money systems that we have in place? Do farmers and farm hands still move the food? Is there a financial incentive for them to do so, or do we have some sort of primitive barter system? Is there oil and gas to get distribution networks going again? How do you pay truckers to work, if money doesn't have people's faith of value?
After things calmed down a bit, there would have to be some kind of 'provisional' society formed. I don't know what it would look like. City-States in loose coalition, trying to be as 'American' as possible?
Best bet to survive it, assuming your number isn't up to begin with, is probably the tried and true rural mountain homestead, as self-sufficient as possible. And that only works if we don't have so much debris thrown into the atmosphere that it's tough to grow anything because it is too dark.
This is pretty worst-case doom and gloom. I don't beleive that this is going to take place anytime soon. It is also entirely theoretical- we have no numbers whatsoever to work with. If this were to happen this month- with my health situation, my financial situation and my location- I'm screwed. Game over. If I thought that this was going to actually happen, and I don't, and if I had serious resources, I'd be as far away from the coast as I could get, on arable land, away from other people, and kitted out as best I could be. I would also not let anyone know who I wasn't prepared to feed clothe and house that I was prepared. Anonymity and being almost impossible to find are a better defense than a squad of armed Marines.
Or the things could miss us completely. Or maybe they aren't there at all.
There are other reasons that the fleets could be putting to sea, including those actually cited. I am in the DC area, and have decent sources. Not hearing anything at all. It *is* odd, but I am not seeing anything else that is particularly alarming.
Military equipment moving by rail? Does it all the time. And we are at war. I remember hearing a lot of talk in the mid-nineties about such movements, and 'prison cars', complete with built-in shackles, are being fabricated at some plant somewhere, and there are a bazillion white school busses in Texas somewhere for use by the UN occupation army. I mean, c'mon.
I was in the SF Bay Area during all of that. Apart from Waco and Ruby Ridge, and Clinton's cast of cartoon characters trying to disarm us and tax us all to death, I saw a COG site go up in Napa, and two actual honest-to-goodness black-painted Bell Jet Rangers with no markings on them, at Buchanan Field in Concord. I saw them from ten feet away, sitting behind a low cyclone fence. A few inquiries revealed that they belonged to the Sheriff's Department. I heard a *lot* of wild stuff. I *saw* very little happening.
As a matter of personal philosophy, simply structuring one's existance for *any* kind of large upheaval or disruption- whether it be an all-out nuclear event, asteroid strike, another Democratic Administration, or whatever, to my mind, requires approximately the same defensive measures. Get away from crowds of people, be able to feed, clothe, house, doctor and defend yourself from whatever comes along, rely only on God and your own two hands.
The third object is a known object, asteroid Itokawa, which will make it's closest approach on Jun 27. At about .0129 AU, which is 600,000 miles, give or take.