Guralp Systems CMG-3ESP Installation - Manual (Page 2)

Cover
Backfill
Dry sand
Marble or
granite plinth
Polystyrene
shielding
Sensor
Signal cable
Installing in a pit or posthole
1
2
4
3
Check you have all necessary equipment, and select a
suitable location for the pit installation. You will need
- the sensor and other seismic equipment;
- an angle-grinder, if mounting on bedrock;
- otherwise, a supply of dry sand and a marble or
granite plinth for mounting the sensor;
- a protective shield of polystyrene or other suitable
material.
Dig a pit at least 60 cm deep at your chosen location, down
to the bedrock if possible.
On bedrock, use the angle-grinder to plane off part of the
surface. Clean the hole and go to the next step.
On compacted subsoil, pour a layer of fine sand over the
bottom of the hole, and mount the sensor on the granite
plinth on top of this sand layer.
Connect the sensor cables, and level and unlock the
components as described overleaf.
Check the system is working, and cover the sensor with its
protective shield.
If you are installing in a cased pit (as in this picture),
install the digitizer and power supply inside if possible, and
seal the installation with a weatherproof cover.
Otherwise, backfill over the shield with fresh soil. Mark the
sensor position, e.g. with its GPS unit. Install the recording
equipment and batteries, if used, in separate pits.
MSH-030-0001-A : Page 2 of 2