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Mr, Dale Ream Cooley Gravel Company 20 !.;arch 1975 Page 4 attenuated when they reach the seismometer. As a result all measurements of displacement, veioci-hj, and acceleration were scaled as though the observation site were at ttte corner of Forest and Vine Streets. This v!as done by increasing the ground motion values (measured at GOL) by an attenuation factor so that accurate ground motion values at the nearest residential sire could be obtained, Nicholls, et.al, (see footnote) have established the follov!ing empirical attenuation rates for the three orthogonal co~~ponents of the particle velocitye vertical: 0,071 (--~~- )-1'7~ ~i radial: 0,052 (. W~~ )-1'63 transverse: 0.035 ( ~f~ }-1.28 ~~here D = distance from blast to seismometer W = vleight of charge per delay The results of this analysis, of the Cooley blast of E>/8/72, was compared to the values independently obtained by measurements of an RFT-250 Strom i5;otion Accelerometer. Butler and l~umamoto calculated a maximum velocity of 0,27i~sec, based on accelerometer measurements. A velocity of 0,28in sec. was obtained using the Bergen Park (GOL) seismometer records and the prescribed equations (table 1). The velocities of the 6/17/72 blast :vere 0,08in/sec. by both methods. 4'h is blast was the largest one set-off at kiorrison Quarry, The 6/8/72 blast v!as monito_^ed at one forth the distance to the nearest residence which accounts for its large velocity, Table 2 gives the results of four of the largest blasts. The 11/28/73 blast produced the 1_argest velocity at the residential site v!ith the exception of the 10,450 lb, blast of 6/17/72, The velocit;~ fer this 5750 lb, blast was 0,026ir_/sec, which is reasonable if compared to the 6/17/72 bla.~t, According tc the L'SB;.I Bulletin 656 the velocity of 0,026in/sec, is below the level of perceptibility. According to this Nicholls, et.al., "Blasting Vibrations and their Effects on Structures," USFi,i Eul.letin 656, 1971,