[meteorite-list] falls per year

From: Jeff Grossman <jgrossman_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:13 2004
Message-ID: <4.3.2.7.2.20010228082932.028e0958_at_127.0.0.1>

Here's a fresh estimate of the number of RECOVERABLE meteorite falls on the
earth each year. I don't know what the other workers have done, but this
is a fairly simple way to get a minimum estimate:

The most densely populated places on earth have the highest recovery rates
of meteorite falls. One such place is Japan. Over the last 20 years of
the 20th century, 10 falls were recovered there: Aomori, Tomiya, Kokubunji,
Tahara, Mihonoseki, Senboku, Neagari, Tsukuba, Kobe, and Sayama. The rate
was almost as high (9 meteorites) between 1920 and 1940, so this is not an
anomalous statistic. The surface area of Japan is 3.73e5 km^2, but nothing
is ever recovered on sparsely populated Hokkaido, so the effective area for
this calculation is 2.94e5 km^2. We can now calculate the number of falls
per year per km^2, and then extrapolate this to the surface of the entire
earth (5.12e8 km^2). Assuming my numbers are right for all these areas, we
get 870 falls/year on earth, which we can take as a lower limit on the true
value.

This calculation assumes that the Japanese are 100% efficient at recovering
all falls in the country, which is not likely. Adding another fudge factor
for this which I'll conservatively place at 0.3 (30% efficiency), we get an
adjusted figure of 2900 falls/year on earth. If 70% of the earth is ocean,
we get a figure of 870 falls/year just on land.

There is no object-size limit on this calculation, it's just based on
recoverable falls. Obviously it is biased toward bigger things.
Dr. Jeffrey N. Grossman phone: (703) 648-6184
US Geological Survey fax: (703) 648-6383
954 National Center
Reston, VA 20192, USA
Received on Wed 28 Feb 2001 08:59:22 AM PST