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1 of the DuPont book. You can find it with the <br /> 2 Bureau of Mines, government agency and so on. <br /> 3 These are values that they use. <br /> 4 The best descriptor for measuring <br /> 5 vibrations and the most common I should say <br /> 6 descriptor for measuring vibrations is peak <br /> 7 particle velocity and this is measured in inches <br /> 8 per second. As far as having value you have to <br /> 9 use it and understand what it means so here's <br /> 10 some values. <br /> 11 If you have a peak particle velocity of <br /> 12 12 you're looking at the fall of rocks in <br /> 13 underlining tunnels. If you have a peak <br /> 14 particle velocity of 7.6 you have a 50 percent <br /> 15 probability of major plaster damage. If you <br /> 16 have a particle velocity of 5.4 you have a 50 <br /> 17 percent probability of minor plaster damage. <br /> 18 If I said major before it was a slip of the <br /> 19 tongue. It's major for 7.6, minor for 5.4. <br /> 20 Besides all the damage from blasting -- <br /> 21 and all our criteria is based on plaster because <br /> 22 we believe it to be the weakest structure in the <br /> 23 house. Some houses don't even have plaster now. <br /> 24 They're better than that. <br /> 25 So the threshold of blasting is 2.8 and <br /> L 29 <br /> * * * CAPITOL CITY REPORTERS * * * <br />