Something happened to make my original post non-answerable, so I have
simplified and posted my question(s) here again.  No on has yet answered or
commented.

Suppose that the (once) unthinkable happens: one (or, God forbid,
more) WMD go off in some urban area of the USA, and the government
declares martial law.
http://www.newsmax.com/archives/articles/2003/11/20/185048.shtml
Citizens would likely feel profound fear, grief, confusion, and
distrust of their government. There would be much anxiety and agitation.

What would be the practical day-to-day change for the those citizens
who do NOT fit any terrorist profile?  What about observable changes
in lifestyle and behavior? Would you consider emigrating to
Canada or another country?
   
Finally, assume you're personally in good shape: you own your own home
in a small-town, your family is safe, you have enough food and water
and shelter indefinitely, and you have no more than $100K in any bank
(for FDIC protection). How would you best protect your *other* assets in
this uncertain world? Would you leave deposited dollars in an
FDIC-protected US bank, or would you convert them into gold?
diamonds? Other currencies? US land? Land abroad (if so, where?)

Millions of people may have to face this question. Better to consider
it *before* the fact: Given the chaotic nature of a world gone mad,
where will be the safest place to park your assets?

In a world gone mad, the only assets of any value will be tangible
goods such as food, medicines, potable water, basic weapons and
ammunition, and somewhere to live while the food, water & stuff last
out.

A good cave in the hills could be useful, also some farming implements
and seed. Maybe a saw, a hammer and some nails and plans for 'How to
Build an Ark'.

Your mobile phone, tv, CD-player, car, computer and such like might
make interesting ornaments.

Start collecting NOW and don't forget a copy of the Bible or the Koran
or whatever so you that can pray that you are only having a nightmare.

Oh and please don't count on me to give you any more helpful Comments,
because I intend to become the new Emperor of the post-Nuclear
Hereafter, and I won't have time to help anybody but myself, Daisy and
maybe Pinkfreud.

OK, Leli can join my Court, as well.

And fp-ga, who also seems to know a thing or two.

Anyhow, there will be a very strict rule: No Hangers On!

Thank you for your response, although it indicates that I was unclear
in my question.
   I do not assume the US will be unliveable, or that gangs of thugs
will roam an anarchic country. Quite the contrary: I assume martial
law and United States that other countries may no longer invest in,
thus drastically devaluing the dollar. Under such circumstances, what
would be the most intelligent method of to storinf value: gold,
diamonds, land, land in foreign countries, something else?

The world provides a multitude of risks, some combination of which
will doom any single asset class. The key to safety is
diversification. If you buy long term bonds, there is the risk that
rising interest rates will make them worth less. If you buy gold,
there is the risk that a safe world will make the price of that
commodity will go down. If you buy stocks, economic problems
(including terrorism) can harm there earnings and cause there price to
decrease. If you have cash (insured short term securities) inflation
can destroy your wealth over time. If you think you can outsmart the
markets you can make a lot of money when you are on a roll, but your
profits can also evaporate quickly when the trends go against you.
Any single class of assets can be destroyed, diversification is the
key to safety. If you set up your financial assets so that what causes
one of them to go down makes another rise even more, then you have
some safety.
I recommend 25% Gold Bullion, 25% long term T-bills, 25% equities (I
like the Wilshire 5000), 25% Cash. As the world changes around my one
or more of my asset classes is always positioned to benefit.