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Monday, October 9, 2006
Curiously Low Yield in Reported North Korean Bomb Test
The United States Geological Survey is now reporting the magnitude of the claimed North Korean nuclear test as 4.2. This seems to be curiously low. Now, estimating explosive yield from the body magnitude of a seismic event is a tricky business, and requires knowledge of details such as the depth of the detonation and the geological properties of the surroundings, but a magnitude around 4.2 is what you'd expect for a detonation of around one kiloton. The “natural size” of a crude fission bomb is in excess of 10 kilotons, from which you'd expect a magnitude closer to 5 (recall that the Richter scale is logarithmic). We'll have to wait for results from the Comprehensive Nuclear Test-Ban Organisation seismic network to refine the yield estimate, but it's worth noting that if the USGS figure of 4.2 is confirmed and no radionuclide release is detected, there is no real evidence that a successful nuclear test was conducted at all. A yield in the low kilotons could simply be the result of blowing up a big pile of high explosive, something which has been done on numerous occasions to calibrate seismic networks, or it's possible the nuclear test resulted in a fizzle yield. It is certainly possible to build nuclear weapons with yields of one kiloton and below—the W-54 warhead of the Davy Crockett nuclear bazooka had a variable yield of only 10 to 20 tons, but that requires a much more difficult to build implosion system to compress a core so much less than a critical mass before detonation, and it is very unlikely that a low kiloton yield device would be used in an initial test. See Fourmilab's on-line Nuclear Bomb Effects Computer for estimates of the effects of surface and airburst detonations with yields between 10 kilotons and 20 megatons.Posted at
16:52
Reading List: Automotive Atrocities
- Peters, Eric. Automotive Atrocities. St. Paul, MN: Motorbooks International, 2004. ISBN 0-7603-1787-9.
- Oh my, oh my, there really were some awful automobiles on the road in the 1970s and 1980s, weren't there? Those born too late to experience them may not be fully able to grasp the bumper to bumper shoddiness of such rolling excrescences as the diesel Chevette, the exploding Pinto, Le Car, the Maserati Biturbo, the Cadillac V-8-6-4 and even worse diesel; bogus hamster-powered muscle cars (“now with a black stripe and fake hood scoop, for only $5000 more!”); the Yugo, the DeLorean, and the Bricklin—remember that one? They're all here, along with many more vehicles which, like so many things of that era, can only elicit in those who didn't live through it, the puzzled response, “What were they thinking?” Hey, I lived through it, and that's what I used to think when blowing past multi-ton wheezing early 80s Thunderbirds (by then, barely disguised Ford Fairmonts) in my 1972 VW bus! Anybody inclined toward automotive Schadenfreude will find this book enormously entertaining, as long as you weren't one of the people who spent your hard-earned, rapidly-inflating greenbacks for one of these regrettable rolling rustbuckets. Unlike many automotive books, this one is well-produced and printed, has few if any typographical errors, and includes many excerpts from the contemporary sales material which recall just how slimy and manipulative were the campaigns used to foist this junk off onto customers who, one suspects, the people selling it referred to in the boardroom as “the rubes”. It is amazing to recall that almost a generation exists whose entire adult experience has been with products which, with relatively rare exceptions, work as advertised, don't break as soon as you take them home, and rapidly improve from year to year. Those of us who remember the 1970s took a while to twig to the fact that things had really changed once the Asian manufacturers raised the quality bar a couple of orders of magnitude above where the U.S. companies thought they had optimised their return. In the interest of full disclosure, I will confess that I once drove a 1966 MGB, but I didn't buy it new! To grasp what awaited the seventies denizen after they parked the disco-mobile and boogied into the house, see Interior Desecrations.
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00:26