wds> http://ntrs.nasa.gov/search.jsp?R=20110016611 is about the previous largest blast before Chelyabinsk, about 70 kilotons worth of bang near Sulawesi Indonesia. Nobody appears to have directly noticed it, but a worldwide network of "infrasound" detectors did, and apparently every blast of this nature will be detected by same from here on out. ---------- I think NASA should surf harder: https://www.youtube.com/watch?v=iAtqySUimdo --rwg More recent, less convincing: https://www.youtube.com/watch?v=05kzqyg2hEI There's also a bunch of vids on a 26 Sep 11 Argentine fatality. http://www.youtube.com/watch?v=XsWOnTMZaBg Here's a vid by a Russian kid pretty clearly showing the zinc plant not failing until the arrival of the sonic boom: http://www.youtube.com/watch?v=SRSrdOfbnHI Presumably, compression of the domed roof blew out the wall(s): http://rt.com/files/news/meteorite-crash-urals-chelyabinsk-283/photo-user-34... Could the lack of big pieces indicate it was just a big, dirty snowball? Or could the fragmentation of a big rock entail positive feedback? E.g., with a hammer, it's a lot easier to break small rocks than big rocks. (And essentially impossible to break hunks of iron.)