Horrific video of West explosion (warning loud noise):

[joshcryer]

Wow... that poor girl.

Oh, it just occurred to me that the dad probably couldn't hear her either.

[joshcryer]

1. Another video (no explosion, just shows the town being interested in it):

This is horrible. All those people looking to see what was happening!

[Deep13]

2. Was she holding the camera vertically?

Weird framing.

[joshcryer]

3. You can see the dad in the rear-view mirror.

And yeah, holding vertically. Phones really should fix that...

[snooper2]

19. most smart phones do, if you hold it on it's side with video or picture

the phone auto adjusts making for better viewing on standard desktops

[joshcryer]

20. Yeah, I mean, phones should record in a higher resolution...

...and allow you to post HD vertical (for viewing on other phones) or HD horizontal.

Basically a 1920x1920 CCD, software would then clip off 840 pixels in either direction for the view, but it'd be recorded at 1920x1920. When you went to publish it, you'd have the option to go with the horizontal or vertical view.

[Posteritatis]

7. It's a very common thing with phone video. Almost the default. (nt)

[66 dmhlt]

13. If you select some special Setting when switching from photo to video ...

Like the "Anti-Shake" feature that's pretty common, it will have a pop-up window when you switch to video that is ONLY oriented in the Landscape view. It's a good reminder that you should probably avoid the Portrait orientation for video.

(Of course you can turn that Warning off, and although it's annoying, I like the reminder.)

[napoleon_in_rags]

4. Analysis:

Based on speed of sound, latency between flash and boom is 20 frames (at 30 fps) so viewer is 777 feet from blast. I'll bet somebody with more knowledge of mics than I could get a ballpark idea of the power of the blast, based if nothing else on the amount of of DB needed for somebody to lose their hearing, and the distribution of energy 777 feet away from a blast. It must have been huge.

[Berlin Expat]

5. Just off the cuff

I'd say an explosive yield of about one kiloton. Maybe a little more - like a small battlefield tactical nuke.

[joshcryer]

6. I took a screenshot of the one frame where the blast is most intense:

[napoleon_in_rags]

9. So long as you're looking, go a few frames back if you have the software to do so.

Notice the frame right before the white light, there is this weird flare on the left, with all the rest of the fire unchanged. The conspiracy sites are calling it "the missile". I don't think so, but it really paints the picture of something super powerful, something so intense that it messes with the normal functioning of the camera, long before the shockwave hits. That was one HELL of a blast...

[joshcryer]

11. Phone cameras use a rolling shutter.

Looks like that's just a frame where the intense light of the fire lit up the smoke and then in the next part of the shutter it filled out the entire CCD.

[napoleon_in_rags]

15. Ah, so if I understand...

Say frame 40 had the bright white light, and frame 39 was the previous one, then the light from frame 40 was SO bright that it bled over into frame 39? That's pretty incredible, at least I've personally never seen it happen with my digital movies. I'm surprised they weren't a little bit blinded in addition to having temporary hearing loss!

[joshcryer]

16. I think they both lost some hearing, it was definitely messed up.

I would have to know the camera model to know for certain if that artifact is from the rolling shutter though. It's not a physical shutter, it's electronic. And depending on the camera it could be horizontal or vertical. Since he was holding it vertically it must then have been a horizontal rolling shutter to cause that artifact. If you knew the model of the phone and maybe asked google it would probably resolve it definitively. I deleted the screenshots I made or I'd upload them, but I really can't explain it other than that.

[napoleon_in_rags]

23. Best guess I've heard so far. I was wondering originally thinking about EMP.

You get a lot of hot metal moving around really fast as in an explosion, I could imagine it sending out some brief intense magnetic waves that could mess with electronics Military has documented it:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA396879
Which from a brief skimming of that, seems unlikely to be the culprit at such range. You are probably have the right idea.

[66 dmhlt]

10. ~ 140-165 dB for Acoustic Trauma (Acute) to Cause NIHL (Noise-Induced Hearing Loss)

Good Table divided into Examples of Noise - dB Levels - Exposure Time Limits - Comments

http://www.cdc.gov/healthyyouth/noise/signs.htm

And one from a medical presentation at Grand Rounds:
http://www.utmb.edu/otoref/grnds/Hear-Loss-Noise-000110/Hear-Loss-Noise.htm

(And yeah, I'm a physician who actually is deaf in one ear and profound hearing loss in the other from Ménière's disease)

[napoleon_in_rags]

17. So it must have been up in that 140-170 db range when they heard it.

The equations for how sound gets quieter at distance allow us to know the original sound level, but what I can't figure it how to convert that to joules - a measure of the energy needed to make that much noise. If I could find that, I could get a lower bound of the power of the blast in terms of a unit like kilotons. All the equations are in terms of watts not joules though, and to convert it I would need to know the precise duration of the original blast, which is hard to meaningfully define though. But plugging in 1ms and a higher estimate of the original db, the blast was the equivalent of several hundred tons of TNT. Its hard to say if this is meaningful though. Wish I did more physics and engineering.

web resources:
Estimating Sound Levels With the Inverse Square Law
http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/isprob2.html
DB to watts
http://www.convertworld.com/en/power/dBm.html
joules to kilotons
http://www.unitconversion.org/energy/joules-to-kilotons-conversion.html

[Heather MC]

8. I hope they are ok. This is so sad. Do not Read the YT comments

The Stupidity of some people, will make your eyes bleed

[progressoid]

14. I've stopped reading youtube comments.

Even the most innocuous video can have awful, hateful, idiotic posts. Save your soul, don't read youtube comments.

[Fantastic Anarchist]

12. Wow!

That was insane!

I heard that people could hear it and feel it all the way over in Arlington (between Dallas and Ft. Worth).

[pinboy3niner]

18. USGS recorded it as a 2.1 seismological event

And the blast reportedly was felt 100 miles away.

K&R

[eissa]

21. I teared up for the little girl

She sounded so scared. Hope she's ok.

[NutmegYankee]

22. She's OK.

She also got her hearing back. http://www.nbcnews.com/video/nbc-news/51581919/#51581919