My eyes are tired and I realized I had not kept all the zeros straight. As the saying goes, a trillion here, a trillion there, and soon you're talking about real money.

Here's a correction.

The usual method of establishing an asset's value is take a look at the income it earns per year, and
then to use some kind of long term interest rate to come up with a number. For example, the US
national income per year used to be about $40,000,000,000,000 per year. Assuming a long term
interest rate of %5, you come up with a value of $800,000,000,000,000. More accurately, that
would be $800,000,000,000,000.00.

Use a long term interest rate of 7%, and you come up with $960,000,000,000,000.00 . But
just for the sake of simplicity, let's go with %5 and $800,000,000,000,000.00

You're right about the effects of ocean impacts - a continent does not have to be directly hit to
cause damage - instead, the impactor could hit in the ocean, and the resulting tsunami will pretty
much wash away everything along one of its coasts. So instead of losing the whole continent, only
a part of that $800,000,000,000,000.00 will be lost.

Take as an example the next occurence of the Stallings Island impact, where everything in the US
from at least the Carolinas to Florida was lost. People like living on the coasts, and most cities are
located on rivers. So let's say that area's part of the United States's value s 15%, or
$120,000,000,000,000.00 of the $800,000,000,000,000.00 total.

The next problem is to identify how often that area is affected by the impact of a small piece of
space junk - a small asteroid or comet. I say "often", because of course over the course of time
that area will be hit several times.

Here, experience is the only way to form a reliable estimate. Looking back over the last 10,000
years, we find the Stallings Island area was hit twice, once by tsunami's from a "small" impactor,
and once by the blast and tsunami of a "medium" one. So the historic odds are 1 hit per 5,000
years. Your own personal odds may vary, but that's the observed historic odds for this area - :p)

To form an estimate of the dollar value of annual risk, you multiply the value times the odds. In this
case, that's

$120,000,000,000,000.00 times
1 hit /5000 years

You come up with an annual risk of
$24,000,000,000.00 per year for just the South East coastal area of the United States. At a
7% long term interest rate the annual risk would be just shy of $35,000,000,000.00
Remember, that's $35,000,000,000.00 per YEAR, in other words each and every year.

If you use other numbers your results will be different. For example, we know nothing about any
of the smaller impactors which hit the area of the South East United States in the last 10,000
years, and the areas they blew away or washed away.

But in every case where the estimate is based on data that in any way reflects reality, your results
will be serious.

EP