5 installing in pits – Guralp Systems CMG-6TD User Manual
Page 23
Installing the 6TD
8. Cover the instrument with thermal insulation, for example, a 5 cm
expanded polystyrene box. This will shield it from thermal
fluctuations and convection currents in the vault. It also helps to
stratify the air in the seismometer package. Position the thermal
insulation carefully so that it does not touch the sensor package.
9. Ensure that the sensor cable is loose and that it exits the seismometer
enclosure at the base of the instrument. This will prevent vibrations
from being inadvertently transmitted along the cable.
4.5
Installing in pits
For outdoor installations, high-quality results can be obtained by constructing
a seismic pit.
Depending on the time and resources available, this type of installation can
suit all kinds of deployment, from rapid temporary installations to
medium-term telemetered stations.
Ideally, the sensor should rest directly on the bedrock for maximum coupling
to surface movements. However, if bedrock cannot be reached, good results
can be obtained by placing the sensor on a granite pier on a bed of dry sand.
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Issue F - February 2014