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' VisRaTECH® <br />material. <br />It should be noted, however, that it is almost impossible in actual practice to visually determine if <br />1 the recorded peak vibration on a typical seismogram is actually within the Bureau's 4-12 hertz <br />range. This is because Bound vibration is usually a complex mixture of many frequencies, which <br />cannot be accurately separated by visual analysis ofa seismogram. <br />' Proper implementation of the Bureau's limit can only be accomplished by a computerized <br />technique, which analyzes the seismographic data in terms of both peak particle velocity and <br />' frequency. <br />' Figure 4 is a graphical representation of the USBM recommended criteria as shown in the <br />velocity versus frequency curve. The vibration analysis of the recordings from the blasts aY <br />Trapper Mining are plotted on the criteria curve (Appendix C). <br />' ESTIMATED PEAK PARTICLE VELOCITY <br />In determining whether a structure has been damaged by blast related activity, two factors are of key <br />importance. First is the amount of energy; and second, the distance a structure is from that energy <br />source. <br />The vibration parameter, which is used to measure potential damage, is called peak particle velocity <br />(PPV). PPV is defined as how fast a particle is moved by passing seismic waves, measured in <br />inches per second (ips). It is based on two simple concepts: The stronger the energy source, the <br />greater the vibration levels; secondly, the greater the distance from the source the less the vibration <br />levels. <br />Scaled Distance is a fundamental relationship between distance in feet from the blast to the <br />recording instrument or point of concern and maximum explosive charge weight in pounds. <br />Dg = D <br />~W <br />Ds =Scaled Distance <br />D =Distance in Feet <br />W =Pounds per delay <br />The often quoted and referenced general use Velocity Attenuation Formula published in the DuPont <br />Blaster's Handbook (16th Fdition, Page 426) is: <br />V =160 (Ds) "i.6 <br />Using this formula one can estimate the peak particle velocity of a seismic wave passing through <br />the structure. Records show distances and explosive weight most pertinent to affecting the <br />structure. Information provided by Trapper Mining, along with the data derived from the <br />previously discussed formula, yields estimated peak particle velocities, which can be found <br />accompanying all the associated data in Appendix B. <br />9 <br />