Analysis of information sources in references of the Wikipedia article "Chelyabinsk" in English language version.
[Interviewer:] Where was most of the energy released as this object made its way through the atmosphere? [Subject:] In this case the final destination, which seems to have been the largest deposit of energy, was somewhere around 15 to 20 kilometers altitude. The actual fireball probably started significantly higher than that, maybe 50 kilometers, but most of the energy was apparently deposited during that last explosion lower in the atmosphere.
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