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A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors
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|Title:||A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors|
show 28 moreBorovicka, J.
de Groot-Hedlin, C.
Le Pichon, A.
|Date Issued:||14 Nov 2013|
|Publisher:||Nature Publishing Group|
|Citation:||(2013) A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors. Nature, 503:238-241|
|Abstract:||Most large (over a kilometre in diameter) near-Earth asteroids are
now known, but recognition that airbursts (or fireballs resulting
from nuclear-weapon-sized detonations of meteoroids in the
atmosphere) have the potential to do greater damage than previously
thought has shifted an increasing portion of the residual
impact risk (the risk of impact from an unknown object) to smaller
objects. Above the threshold size of impactor at which the atmosphere
absorbs sufficient energy to prevent a ground impact, most of
the damage is thought to be caused by the airburst shock wave, but
owing to lack of observations this is uncertain. Here we report an
analysis of the damage from the airburst of an asteroid about
19 metres (17 to 20 metres) in diameter southeast of Chelyabinsk,
Russia, on 15 February 2013, estimated to have an energy equivalent
of approximately 500 (6100) kilotons of trinitrotoluene (TNT,
where 1 kiloton ofTNT54.18531012 joules).Weshowthat a widely
referenced technique of estimating airburst damage does not
reproduce the observations, and that the mathematical relations
based on the effects of nuclear weapons—almost always used with
this technique—overestimate blast damage. This suggests that earlier
damage estimates near the threshold impactor size are too
high.Weperformed a global survey of airbursts of a kiloton ormore
(including Chelyabinsk), and find that the number of impactors
with diameters of tens of metres may be an order of magnitude
higher than estimates based on other techniques. This suggests
a non-equilibrium(if the population were in a long-term collisional
steady state the size-frequency distribution would either follow a
single power law or there must be a size-dependent bias in other
surveys) in the near-Earth asteroid population for objects 10 to
50 metres in diameter, and shifts more of the residual impact risk
to these sizes.
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HIGP Faculty & Researcher Works|
Garces, Milton A.
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