Guralp Systems CMG-3T - Manual (Page 19)

Operator's guide
crushed rock, with a high proportion of rock flour and fine
particles, makes excellent packing material. Alternatively, a
mixture of 3 mm grade angular coarse grit with around 30%
medium grit gives good results. Moisten the packing material
in the hole and ram firm.
4. Lower the instrument to the bottom of the hole, but without
slackening the lifting cable.
5. Fill more packing material around the instrument for about 30
cm, moisten, and ram firm.
6. Use the inclinometer to check that the instrument remains
within its tilt tolerance (± 2°).
7. Continue filling, moistening and packing until the instrument
is buried, checking that the tilt remains within tolerance.
8. Release the strain on the lifting cable, and allow the packing
material to settle for 24 hours.
9. If all is well after the settling period, release the lifting tackle,
coil a tail of the lifting wire into the top of the hole and backfill
almost to the surface.
10. Ensure that the signal cable is slack, and fix it to a support at
the top of the hole.
11. Ram a split wooden bung into the top of the hole, and cover
with sandbags.
12. Attach the signal cable to your recording equipment or
breakout box. Power the sensor, and unlock it. Carry out
preliminary tests using a hand-held control unit, if required.
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