[meteorite-list] Article : 21st Century Meteorite Falls, Part Two

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Thu, 20 Oct 2016 15:57:46 -0400
Message-ID: <CAKBPJW8noNqMUM_hS06Eh-Y786cROD3PgH48COpu+Nmanr6Pew_at_mail.gmail.com>

"...In the first 10 years of the 21st Century, we have seen 58 new
meteorite falls (as of this writing). As we close out the first decade
of this new century, let us examine some of the facts and numbers
surrounding these recent falls. For the purposes of this article, we
will only examine those falls which have been officially recognized by
the Meteoritical Society. There have been a few documented falls that
have not been approved yet (Zunhua and Cartersville), so these falls
will not be included in this analysis..."

I wrote the above introductory paragraph nearly 6 years ago (early
2010) when I did my first analysis of recent meteorite fall
statistics. More than 5 years later, we have had 40 more
officially-recognized falls. In that same span of time, we have also
had Breja, Addison, Oslo, Mahbse Aarraid, and the recent White
Mountains fall that are well documented falls that have not been
approved or published in the Met Bull. A quick look at the overall
numbers shows a very slight increase in the number of approved falls
in the last 6 years compared to the previous 9.5 years. This is likely
due, in part, to increased awareness of meteorites and increased
recovery rates.

Also, it seems that NonCom has been moving a bit faster to approve new
falls and publish them in the Met Bull. Taking all of these recent
falls into account, we have now had 98 official falls since the year
2000. If one chooses to include the recent unofficial falls which will
likely be approved in the near future, then we have had over 100
meteorite falls in the 21st century.

So, in the first 16 years (2000-2016) of this century, we have
averaged just over 6 approved falls per year. This represents an
uptick in the average number of approved falls compared to the
previous period of 2000-2010 where the average was 5. This is not so
clear cut though, because a couple of older falls were approved in the
years since, including Zunhua (as it was known in 2010), which was
approved in late 2015 as Xinglongquan. For tidy conversational
purposes, it's safe to say that we expect about 5 to 6 new approved
falls each year. A number of 5 per year being more conservative and
closer to 6 if you take into account that some falls are not recovered
or approved until a year or more after the date of their fall.

Now let's take a look at the numbers and have some fun with them :
Which petrologic type do you think was the most common type recovered
during the first 16 years of this century?

Well, it's safe to say that it is an ordinary chondrite. No surprises there.

More specifically, we have a tie between L6 and H5 chondrites at 23 each.

Anyone want to guess what the third most common type is?
The third most common is the L5 chondrite with 10 approvals.
Well, surely the fourth most common is probably an H chondrite, right? Wrong.

The fourth most common type is the eucrites with 7.

Wait, that seems like too many Vestans! How can eucrite be in the top
4 common types? The answer is simple, it's because we are playing
semantics with petrologic grades here.

There have been 23 L6 chondrites, 23 H5 chondrites, 10 L5 chondrites,
and 7 eucrites. But, there are many subtypes of H and L chondrites
that are approved by NonCom, compared to the much smaller clan of
eucrites. In total, there were 42 L chondrites and 40 H chondrites of
various petrologic grades (L3, L4, L5, L6, etc) compared to just 7
eucrites. Throw in the 10 LL chondrites that were approved and the
numbers become more lopsided in favor of ordinary chondrites over
eucrites - 92 to 7.

After the ordinary chondrites and eucrites, the most numerous of
meteorites recovered from 2000 to 2016 were carbonaceous chondrites
followed by a sprinkling of achondrites of different types.

Worthy of note, thus far there has only been one iron fall (Kavarpura,
2006) and no pallasite falls.

There have been 39 hammer falls to date since Jan 01, 2000 - that is
roughly 40% of known falls.

Number of official falls by country :

USA : 17
India : 12
Morocco : 8
China : 5
Mauritania : 4
Australia : 3
Brazil : 3
Canada : 3
Germany : 3
Nigeria : 3
Turkey : 3
Argentina : 2
Burkina Faso : 2
Czech Republic : 2
Denmark : 2
France : 2
Iran : 2
Kenya : 2
Russia : 2
Spain : 2
Sudan : 2
Algeria : 1
Cambodia : 1
Colombia : 1
Croatia : 1
Ecuador : 1
Italy : 1
Japan : 1
Lesotho : 1
Libya : 1
Madagascar : 1
Mali : 1
Mexico : 1
Norway : 1
Pakistan : 1
Peru : 1
Poland : 1
Romania : 1
Slovakia : 1
Slovenia : 1
South Korea : 1
Tunisia : 1
Uganda : 1
Uzbekistan : 1
Western Sahara : 1
Yemen : 1
Zimbabwe : 1

A few things we can surmise from these country numbers. Obviously the
USA had the most falls. This is largely due to the number of cameras
and observers watching the skies, combined with a robust system of
quickly tracking down falls to recover them. India is somewhat
surprising with the second-most number of falls, and this is due in
part to how densely-populated that nation is. Morocco, despite it's
small geographic size, was in third place. Morocco's performance can
be attributed to the meteorite-savvy nature of the local population.

China is in fourth place, which is very surprising when considering
how big China is in geography and population. Another surprise is
Russia, which had only two known falls. I think China and Russia's
lack of recoveries is due in part to the difficult nature of the
terrain in those countries (compared to a nation like Morocco that has
a lot of desert), and the undeveloped nature of their meteorite
recovery programs.

Although the USA has no government-sponsored program to recover
meteorites in America, there is a thriving culture of participation by
private hunters, which explains the relatively high recovery rate.
This stands in stark contrast to Australia which has a quasi-official
program to recover meteorites, but only has three recoveries to show
for it. Another big country with a small number of recovered falls is
Canada, and once again, I think difficult terrain is responsible for
some of that, and the rest can probably be explained by how
sparsely-populated some areas are.

Number of official falls by petrologic type :

C2-ung : 1
CM : 1
CM2 : 1
CO3.6 : 1
CV3 : 1
EL6 : 1
LL3.2 : 1
LL5 : 3
LL6 : 6
L3 : 1
L4 : 4
L5 : 11
L5-6 : 1
L5/6 : 2
L6 : 23
H/L3 : 1
H/L4 : 1
H3-5 : 2
H3.8 : 1
H4 : 3
H4-5 : 2
H4/5 : 2
H5 : 23
H5/6 : 2
H6 : 4
Eucrite : 7
Howardite : 1
Martian : 1
Ureilite : 1
Iron IIE-an : 1

That?s it for this installment. I?ll see you again in several years.
In the meantime, good luck and happy hunting! :)

21st Century Meteorite Falls (Part One) :
http://www.galactic-stone.com/pages/20falls

Recent Meteorite Falls (updated tally page) :
http://www.galactic-stone.com/pages/falls

Witnessed Falls available for purchase :
http://www.galactic-stone.com/pages/fallcatalog

This article is ? Galactic Stone & Ironworks Meteorites, 2016.
Received on Thu 20 Oct 2016 03:57:46 PM PDT