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,: <br />bir, Dale Ream <br />Cooley Gravel Company <br />20 i::arch 1975 <br />Page 3 <br />season. Seismicity and blast data <br />by a three co,;,ponent short period <br />(designated GLD) since 1950. <br /> <br />}rave also been obtained <br />seismometer in Golden <br />According to I~:r. Doug Getchell (personal communication) of <br />L:actin L:arietta Aerospace, they have been vrorking vrith <br />Cooley Gravel by perio;lically monirr,ring quarry blasts from <br />f::orrison quarry, Eefore Cooley blasts are made, iSartin <br />b~arietta is notified and the seismometers are activated, <br />Two seismometers are used for this monitoring and are located <br />in the same vatrlt as the Colorado School of Lines L.I.:V <br />seismometer station. One of the seismometers is a vertical <br />component Lenioff with a gain of twenty-tr.ousand at one hertz, <br />while the other is a Viking Space Craft seismometer with a <br />gain of 1.7 million at seven hertz. Cooley Gravel and <br />I.'.artin I.:arietta have a mutually ben ificial relationship, for <br />while the Cooley blasts are being monitored, the Viking Space <br />Craft seismometer is bei;ig tested. <br />According to Cooley Gravel there have been 200 quarry blasts <br />from June 1972 through December 1974, 159 of which have <br />sho:vn-up on CSC.; seismometer records, The remaining b7_asts <br />were either of insufficient size to be recorded, or <br />sufficiently small tha+, they were overlooked by the record <br />obs?rver, Records of quarry blasts from 1975 have noi; yet <br />been fully studied. The quarry blasts are identifiable on <br />the seismometer records by their particular characteristics, <br />these being; approximately fifteen hertz wavetrains (on <br />Chatfield records, 2-5 Hz. on GOL), and nearly two second <br />compressional to shear wave arrival times. <br />The first step in obtaining values for ground motion <br />quantities is the measurement of the seismometer trace <br />amplitudes. Ey dividing the amplitude by the seismometer <br />gain, absolttte ground notion at the seismometer site is <br />obtained, This displacement may be related to the velocity <br />and acceleration by the following equation: <br />Acceleration ~ 2'7f(velocity) =(2~Tf)2(displacement) <br />Where: f = seismometer signal frequency <br />However, the seismometers are 8,2 to 14,0 miles from the <br />blast site, which means the seismic waves are greatly <br />