• USGS
  • NSF
  • Iris
  • Iris

Recalibration of IRIS / IDA sensors

Aim of project

At the request of the community, the GSN Network Operators are reviewing the procedures used for calibration and orientation of sensors and adopt common practices where possible. While examining our orientation practices, we began reviewing our procedures for analyzing data from a co-located sensor. This is how we determine the orientation of KS-54000s installed in sand and may prove to be the best way of simultaneously checking calibration and orientation of sensors already deployed.

To permit our field crews to conduct the required surveys as easily and rapidly as possible without sacrificing accuracy and to verify sensor calibration at the same time, we have purchased a compact broadband sensor and DAS for short deployments at the station whose sensor orientation and calibration is to be checked. We selected the Nanometrics Compact Trillium/Taurus digitizer hardware for its compactness, portability and performance. These devices can be operated independently of the existing GSN system and are small enough to be shipped in checked luggage.

After orienting the portable sensor to true North (see illustration courtesy of Nanometrics) and gathering several hours data (such as shown here) while operating in parallel to, but electronically separate from, the GSN system, the sensor will be retrieved and returned to San Diego where its calibration can be verified on a shaketable.