The problem with trying to fake a nuclear test with conventional explosives is that you need to not only get enough of them, you have to make them all go off effectively simultaneously. Besides just a magnitude, a seismic trace shows the types of waves, their orientation, and the time of arrival at the seismic station. For an earthquake, with a good instrument array you can get a three-dimensional picture of not only where the quake started (the hypocenter) and the orientation of the fault that the quake propagated along. For a big enough quake that's measured carefully enough, you can even tell which parts of the fault slipped faster, or a greater distance. A nuclear test is unlike an earthquake in that it is a single point source. There is no fault that takes time to move, and all the initial waves are coming from essentially the same point. This leaves a distinctive "double-pulse" signature on the seismogram. To fake it with conventional explosives, you'd need some very carefully timed fuses to make sure that you blew up the various parts of your huge collection of explosives at exactly the right time so that the impulses would arrive at a remote station as if they'd all come from a single event. This would be very hard to do, and you'd need to know quite a bit about all the intervening geology between your fake test and the seismograph station to get it exactly right.
10:21 AM, October 09, 2006
This test has humiliated China, which has recently spent a good deal of diplomatic effort to dissuade North Korea from going forward with the test. Will they now consider pulling the plug on fuel and food shipments? This Newsweek article starts to ask some of the questions.
Of course, I wonder what the Bush administration will do. But I don't think they're in as much of a position to do anything as China. And of course one wonders about the American political fallout. Obviously, this is a huge failure for Bush's policies. But of course they'll try to spin it as a reason to stay in power.
Just a thought: is there a possibility that N. Korea is bluffing about this? Maybe they just set off a huge amount of conventional explosives underground. But people seem to think this is the real thing.
"What will China do about N. Korean nuke?"
1 Comment -
The problem with trying to fake a nuclear test with conventional explosives is that you need to not only get enough of them, you have to make them all go off effectively simultaneously. Besides just a magnitude, a seismic trace shows the types of waves, their orientation, and the time of arrival at the seismic station. For an earthquake, with a good instrument array you can get a three-dimensional picture of not only where the quake started (the hypocenter) and the orientation of the fault that the quake propagated along. For a big enough quake that's measured carefully enough, you can even tell which parts of the fault slipped faster, or a greater distance. A nuclear test is unlike an earthquake in that it is a single point source. There is no fault that takes time to move, and all the initial waves are coming from essentially the same point. This leaves a distinctive "double-pulse" signature on the seismogram. To fake it with conventional explosives, you'd need some very carefully timed fuses to make sure that you blew up the various parts of your huge collection of explosives at exactly the right time so that the impulses would arrive at a remote station as if they'd all come from a single event. This would be very hard to do, and you'd need to know quite a bit about all the intervening geology between your fake test and the seismograph station to get it exactly right.
10:21 AM, October 09, 2006