[meteorite-list] Sterlitamak

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Tue, 10 Jul 2012 00:50:24 -0500
Message-ID: <BCE5EA748B9E464D9C0555D22D195B5B_at_ATARIENGINE2>

Paul, List,

You're right; the Sterlitamak "crater" is an odd case.

It is neither exactly a "crater" nor merely an "impact
pit," but is intermediate between the two forms::
http://adsabs.harvard.edu/abs/1992AVest..26...82P

The Sterlitamak crater, is 9.4 meters and was formed on
May 17, 1990 by a one-ton iron object. While every impact
differs from others, a description of that crater is of interest:
http://adsabs.harvard.edu/abs/1992Metic..27R.276P

Quote:
    "The Sterlitamak meteorite fell on May 17, 1990 at 23h20m
local time (17h20m GMT) and formed a crater in a field 20 km
westward of the town of Sterlitamak (Petaev et al., 1991).
Many witnesses in South Bashkiria saw a very bright fireball
(up to -5 magnitude) moving from south to north at a ~45
degree angle to the horizon. Witnesses located ~2 km from
the crater observed the fireball glowing right up to the time
of impact, after which several explosions were heard. The
crater was found on May 19. From witnesses' reports, the
fresh crater was 4.5-5 m in depth and had sheer walls ~3 m
in height below which was a conical talus surface with a hole
 in the center. The crater itself was surrounded by a continuous
rim 60-70 cm in thickness and by radial ejecta. Our field team
arrived at the crater on May 23, six days after its formation.
We found the crater in rather good condition except for
partial collapse of the rim, material from which had filled
in the crater up to ~3 m from the surface. The western wall
of the crater was composed of well-preserved brown loam
with shale- like parting dipping 25-30 degrees away from the
crater center. A large slip block of autogenic breccia was
observed along the eastern crater wall. An allogenic breccia
composed of a mixture of brown loam and black soil was
traced to the depth of ~5 m from the surface. Outside the rim,
the crater ejecta formed an asymmetric continuous blanket
and distinct radial rays. The southern rays were shorter and
thicker than the northern and eastern rays. About 2 dozen
meteorite fragments, from several grams to several hundred
grams in weight, were recovered in the crater vicinity. A search
for other meteorite fragments or individuals at distances up
to 1 km southward from the crater was unsuccessful. Two
partly encrusted fragments (3 and 6 kg) with clear
Widmanstatten pattern on a broken surface were found at
a depth of ~8 m during crater excavation. In May of 1991
a 315-kg partly fragmented individual was recovered at a
depth of ~12 m. This sample is a 50 x 45 x 28 cm block
with front, rear and two adjoining lateral surfaces covered
by regmaglypts and thick (~0.5 mm) fusion crust. The
other two surfaces are very rough, contain no regmaglypts,
and have a thinner fusion crust. The preimpact shape of
the meteorite may be approximately modeled as a slab
~100 x 100 x 28 cm. An estimate of the projectile mass
was made based on the crater dimensions. From the
relationships between crater diameter and projectile mass
determined for the Sikhote-Alin craters, the impact mass
of the Sterlitamak meteorite is estimated at ~1 ton (Petaev, 1992).
A separate estimate, based on cratering energy, yields a total
mass of ~1.5 tons (Ivanov, Petaev, 1992). A comparison of
the estimated projectile mass and the weight and morphology
of the individual recovered suggests a fragmentation of the
projectile in the atmosphere and the formation of the crater
by the impact of an agglomeration of individuals. The other
fragments of the projectile are still in the crater."

http://www.somerikko.net/old/geo/imp/refer.htm
"Observers claim that the fireball actually hit the ground.
Impact velocity was estimated to be over 2 km/s and impact
force was equal to 1 ton of TNT. Meteorite made 9.4 meter
wide and 3 meter deep crater into a potato field. Impact
(shockwave of falling meteorite) destroyed potatos in a
area of 100 meter in radius. A 300 kg meteorite was recovered
from 15 meter below surface and it is estimated that there
should be at least one ton more meteorite but deeper in the
ground."

It buried itself!


Sterling K. Webb
-----------------------------------------------------------------------------
----- Original Message -----
From: "Paul Gessler" <cetuspa at shaw.ca>
To: "meteorite-list" <meteorite-list at meteoritecentral.com>
Sent: Tuesday, July 10, 2012 12:19 AM
Subject: [meteorite-list] Sterlitamak


> Ok I read the link to the Sterlitamak meteorite and a couple other
> write ups on it but can't locate the width of the crater.
> I see all the other measurements but missed the crater width.
>
> Does anybody know the answer?
>
> -Paul G
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Received on Tue 10 Jul 2012 01:50:24 AM PDT