Seismic refraction instruments:

E.G.& G. Geometrics ES-2415F with double record length option

24 8-bit channels, 2048 samples/channel, record lengths of ¼, ½, 1, 2, 4 or 8 seconds;

CRT display, hard copy printer;

Signal enhancement capability;

EG.& G. Geometrics DMT-911 digital magnetic tape unit: stores digital records for downloading to computer or playing back into seismograph;

24 4.5-Hz vertical geophones;

24 100-Hz geophones, vertical or horizontal;

2 cables with 12 take-outs each at 35-foot intervals, on reels;

2 cables with 12 take-outs each at 100-foot intervals, on reels;

BETSY "buffalo gun" for detonating seismic sources (industrial blanks, 8-gauge or 12-gauge) under the surface;

Shear wave generator: traction plate - I-beam with spikes, 6 kg and 9 kg hammers.

This system is routinely used to map the water table and top of bedrock to depths of 200 feet in northwest and central Ohio. Greater depths can be mapped if conditions are favorable. Shallow (less than 15 feet) bedrock with water table less than 5 feet poses "masked layer" problems. Shear wave studies of sediments near landfills provide information useful in calculating resonate frequencies and strong motion amplification.

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