Was the 2013 meteor over Russia stronger than an atomic bomb?

Question

Reports of the Russian meteor event (2013) say that it released more energy than 20 atomic bombs of the size dropped on Hiroshima, Japan:

Scientists estimated the meteor unleashed a force 20 times more powerful than the Hiroshima bomb, although the space rock exploded at a much higher altitude. Amy Mainzer, a scientist at NASA's Jet Propulsion Laboratory, said the atmosphere acted as a shield.
The shock wave may have shattered windows, but "the atmosphere absorbed the vast majority of that energy," she said.

http://abclocal.go.com/kfsn/story?section=news/national_world&id=8994311

Really? Wouldn't that have done more damage than was seen? How does the damage depend on how quickly the energy is released?

Just a thought, but aren't atomic weapons detonated above the ground to maximise the effects of the explosive yield? When set off at ground level, a lot of the energy from a bomb goes into excavating the area underneath the device, rather than out to the sides, where it would cause more damage. — Peter J Morgan, Feb 16 '13 at 20:06
Above ground, yes, but not nearly so far above the ground as the meteorite exploded, which was 12-15 miles. — LarsH, Feb 16 '13 at 21:56
What really matters is $\text{Intensity}=I=\frac{P}{A}=\frac{\text{Energy}}{4\pi r^{2}t}$ — raindrop, Feb 17 '13 at 03:58

Luboš Motl · Answer 1 · 2013-02-16T14:56:46.050

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Hiroshima exploded 67 terajoules of energy i.e. $6.7\times 10^{13}$ joules. We may calculate the mass of the Russian meteor assuming that the speed is $v=20,000$ m/s: $$ \frac{1}{2} mv^2 = 6.7 \times 10^{13} $$ We obtain 335 tons. The numbers aren't precise but they're in the ballpark and reasonable. The Russian academy of sciences actually estimates 10,000 tons which would be something like 700 Hiroshimas.

The Hiroshima bomb was harmful because its energy was focused on a small place, several kilometers around the explosion were destroyed. The energy of the Russian meteor was distributed to a much larger area of radius closer to dozens if not 100 km and much of the energy was deposited to the atmosphere, so the local impact was significantly smaller than it was in Hiroshima. If we exaggerate a bit, the energy was spread to 20 times longer distances than in Hiroshima and the dilution scales as something in between the second and third power, so one gets about 500 times smaller "local impact" at the relevant places than in Hiroshima even if we add the factor of 30 (30 Hiroshimas).

Some individual collisions detected on the ground were estimated to have just 1 TJ or so, 67 times weaker than the Hiroshima. The bulk of the energy was deposited to the atmosphere.

But I guess that the main reason why you find the numbers counterintuitive is the widespread antiwar propaganda that prefers to present a nuclear blast as a nearly supernatural event of nearly infinite proportions. This ain't the case. The bomb in Hiroshima was just another bomb, a bit stronger one (plus some annoying radioactive stuff that had other consequences, something that wasn't caused by the meteorite). Five kilometers from the ground zero, they experienced similar symptoms as they did in Chelyabinsk – broken windows and a reasonable but not infinite sound of the explosion. Hundreds of meters from the explosion, things vaporized and the Russian meteor had no place with this much concentrated energy.

edited Feb 16 '13 at 14:56

answered Feb 16 '13 at 13:23

Luboš Motl

179,018

5

Similarly a tropical storm/hurricane release about 10^18 Joules/day. Roughly = a Hydrogen bomb/minute! – Martin Beckett Feb 16 '13 at 15:02
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I'm not sure you made it clear that, neglecting radioactive fallout, the initial damage is caused by 1) radiative heat and 2) acoustic blast wave/sonic boom. In this case, since the event was about 19km above the ground, the heat was not too bad at the surface, especially considering slant range. The acoustic wave was also at a distance, but it still pulverized a lot of windows (2 minutes later), which injured a lot of people who were looking out those windows. Many people injured in Hiroshima/Nagasaki were hurt the same way.

Mike Dunlavey

Feb 16 '13 at 15:06

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It seems to me that using the Hiroshima bomb as a scale to measure the energy output of things that aren't bombs is potentially misleading and politically-charged. – Garrett Albright Feb 17 '13 at 02:23

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Dear Mike, right, 80% of the energy from a nuclear blast is emitted in the form of photons. The fuel just gets heat up to 60-100 million Celsius degrees which means that the typically emitted thermal photons - it's glowing like crazy - are X-rays with energy 10-200 keV. It's sort of important to emphasize that they're X-rays because when we say "thermal", we tend to think about infrared (thermal for room temperatures or close ones). But at those high temperatures of the fuel, thermal means X-ray. – Luboš Motl Feb 17 '13 at 06:04

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@GarrettAlbright Disagree for practical reasons. An explosion of that size is outside the span of normal human experience; and there's a lack of well known natural events that created explosions in the 10-100kt range that could be used instead. – Dan Is Fiddling By Firelight Feb 17 '13 at 18:05

@DanNeely - but we have all seen pictures of the effect of Hiroshima's prompt urban redevelopment. So we have a picture of what 10^11J looks like – Martin Beckett Feb 17 '13 at 18:31

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I've stripped a lot of essentially political commentary. You were a participant and want a copy let me or another mod know, but it wasn't doing anything for the site. – dmckee --- ex-moderator kitten Jul 16 '14 at 22:32

score 6 · Answer 2 · answered Feb 16 '13 at 20:57

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The duration of the energy release has a huge effect on the destructive potential. A single stick of TNT has roughly 1 MJoule of energy which is released in a fraction of a second. [1] Spread the same 1 MJ over an hour and you get 277 W or roughly the same power consumption as an ATI Radeon HD 7970. [2]

Sources:

[1] http://en.wikipedia.org/wiki/Dynamite

[2] http://forums.atomicmpc.com.au/index.php?showtopic=264

answered Feb 16 '13 at 20:57

Tyler Waugh

69

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This begs an important question that belongs tacked onto any energy estimate: do you mean for the one biggest explosion, or for the entire dissipation of kinetic energy of the meteor? The latter "release" of energy was neither instant nor continuous, not like either a stick of TNT nor a smoking game card. I recall a news report of 5 or 6 explosions, and of course there was the impact. Each were relatively instantaneous. Then there was a buildup of heat as the meteor slowed, that energy heated air and debris.
Comparisons to a bomb should be made about the explosions only.
– Bob Stein Feb 16 '13 at 21:26
@BobStein: The impact? I thought the rock shattered in mid-air, so there would have been several impacts. "Some meteorite fragments fell in a reservoir outside the town of Chebarkul, the regional Interior Ministry office said. The crash left an eight-meter (26-foot) crater in the ice." ... – LarsH Feb 16 '13 at 21:56
@LarsH you're right there must have been several. I only saw the one picture of the hole in the lake ice. Multiple impacts further complicates comparing the energy to a bomb. – Bob Stein Feb 17 '13 at 00:11
@BobStein It is a fairly complex problem and depends a lot on how you choose to measure the energy release. It is much easier to use the total dissipation, all you need then is the mass and the velocity. I assumed that the energy estimate was using this measure so the period would be very long. – Tyler Waugh Feb 17 '13 at 03:17
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That same MJ of energy is also less than the energy you extract from a single slice of cake, or a decently sized salad. – Feb 17 '13 at 03:48
Dear Tyler, one hour is a very long time and a GPU card is cooling down a lot during the time - although we usually need to help it to cool down, too. However, no explosion of any bomb takes one hour. The propagation of a meteor in the atmosphere does take some time but it was 1) much shorter than 1 hour, 2) this separation into time may also be reinterpreted as dilution of the power in space because the meteor was moving and yes, most of the energy of the meteor came to higher heights of the atmosphere, much higher than for (nuclear) bombs. – Luboš Motl Feb 17 '13 at 06:06
What I wanted to say but forgot to do so is that as long as the energy is deposited in a fraction of a second, it doesn't really matter how quickly it is deposited, only the total energy matters, simply because there's no time to cool down. The exposed objects get heated to temperature that is dictated by the total released energy, not so much by the duration. – Luboš Motl Feb 17 '13 at 06:08
I think the relevant question here is what method is being used by the scientists who got the several hundred kt estimate from infrasound detectors intended to monitor nuclear bomb tests. – Dan Is Fiddling By Firelight Feb 17 '13 at 18:07
@LubošMotl The hour was simply a demonstrative number that happened to create a nice wattage. The total energy of the asteroid is still released over a long area and a relatively long time. – Tyler Waugh Feb 17 '13 at 19:08

Was the 2013 meteor over Russia stronger than an atomic bomb?

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