14. Proceed to configure the Centaur for use with the Trillium Compact, see
, using the following paragraphs as a guideline:
a. Verify that the connections displayed in the Discovery panel on Centaur Web
interface match the connections on the Centaur digital recorder, see
connection with the Centaur digital recorder" on page 21
b. Select the sensor type from the sensor library. See
the Trillium Compact" on page 58
.
Make sure that the selected seismometer is compatible with the actual
seismometer. For example, if you have a 20s seismometer, select
Trillium Compact Posthole 20s - Default from the Sensor Library.
c. Configure the digitizer sensitivity, see
"Seismometer System Sensitivity
. Typically this will be 40 V peak-to-peak.
2.7.2 Installing a Trillium Compact Posthole in a Cased Hole
Use the following steps to install a Trillium Compact Posthole in a cased hole:
For best results, make sure that the cased hole is dry and the bottom is sealed. If you
are using an existing cased hole, make sure that the hole is not flooded. Additionally,
the inner diameter of the casing should be at least 10 mm larger than the
seismometer to allow clearance for casing joints and to allow space for sand to flow all
around the seismometer when it is installed. See the
Nanometrics technical note 18093
Borehole Drilling Requirements
for details on preparing a cased hole.”
1. Prepare the hole for the installation.
The hole diameter must be large enough to accommodate the seismometer, which has
a diameter of 97 mm. The hole must be covered at the top to protect the seismometer
from the elements such as wind and rain. This cover must secure and stabilize the
electrical and lifting cables, allowing some slack to avoid strain on the seismometer.
2. Obtain very clean dry sand material that will flow easily and not solidify over time.
Aluminum oxide sandblasting material with a coarse grain size is recommended. A more
easily available substitute is washed play sand, however it must be dried prior to use so
Chapter 2 - Installing a Trillium Compact Posthole Seismometer
16889R10 • 2020-11-12
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