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

From: Carl Agee <agee_at_meteoritecentral.com>
Date: Thu, 20 Oct 2016 14:46:30 -0600
Message-ID: <CADYrzhq-v4DR5BijqKQ_t5sOkQQC7ZkDVCboP99BrovhO1Lh7A_at_mail.gmail.com>

Always an interesting topic!

A couple of things come to mind:

Morocco has 8 falls in the 21st century, which you suggest has to do
with the meteorite-savvy population and desert terrain. California has
a very similar area and population density -- also a west facing coast
line, a fair amount of desert, and a mountain range. How many 21st
century falls in CA?

We are over-due for a lunar falls! There are now 265 classified lunars
-- all of them finds. Compare that with 5 martian falls and 177
classified finds, or for example mesosiderites with 6 falls and 261
classified finds. Aubrites have 9 falls and 63 finds.

Brachinites have no falls (40 finds), any others?

Carl


*************************************
Carl B. Agee
Director and Curator, Institute of Meteoritics
Professor, Earth and Planetary Sciences
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126

Tel: (505) 750-7172
Fax: (505) 277-3577
Email: agee at unm.edu
http://meteorite.unm.edu/people/carl_agee/
http://compres.us/about-us/compres-president



On Thu, Oct 20, 2016 at 1:57 PM, Galactic Stone & Ironworks via
Meteorite-list <meteorite-list at meteoritecentral.com> wrote:
> "...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.
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Received on Thu 20 Oct 2016 04:46:30 PM PDT