Guralp Systems CMG-3ESPCD - Manual (Page 14)

CMG-3ESPCD Digital Broadband Seismometer Installing the 3ESPCD
stratify the air in the seismometer package. Position the thermal
insulation carefully so that it does not touch the sensor package.
11. Ensure that the cables are loose and that they exit the seismometer
enclosure at the base of the instrument. This will prevent vibrations
from being inadvertently transmitted along the cables.
3.4 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.
1. Prepare a hole of 60 – 90 cm depth to compacted subsoil, or down to
the bedrock if possible.
2. On granite or other hard bedrock, use an angle grinder to plane off the
bedrock at the pit bottom so that it is flat and level. Stand the
instrument directly on the bedrock, and go to step 7.
3. On soft bedrock or subsoil, you should install a pier as depicted below.
MAN-C3E-0002 14 Issue B - November 2013