We designed respGen as a tool to allow instrument manufacturers and network operators to easily determine the instrument response of any seismograph. In 1994, Pavlis and Vernon published a paper, “Calibration of Seismometers Using Ground Noise”, claiming that if the instrument response of one of two co-located seismometers is known, we can restore the instrument response of the other. The new RespGen program is a highly refined version of the Pavlis and Vernon method.
Nearly every station in the GSN network has an STS-1 co-located on the same pier as an STS-2 or another broadband sensor. Take, for example, the GSN station in Kyrgyzstan. Given a single day’s worth of raw data from AAK.00 (STS-1) and AAK.10 (STS-2), RespGen is able to accurately determine the instrument response of AAK.10 from AAK.00.
Getting the instrument response of an “unknown” sensor from another sensor with a “known” instrument response is now easy.
Our company owns and operates a world-class broadband seismic station called BRU2. The continuous data are shared publicly with IRIS. In February, 2013 Branden (our CEO) set up 3 Nanometrics Trillium Compacts side-by-side to test some new software he was developing to implement the Sleeman method for determining self-noise levels. Here is what the setup looked like:
We then ran the data from two of these sensors through the RespGen program in order to determine the instrument response:
The blue line is the instrument response of the Trillium Compact according to Nanometrics. The green line is the instrument response for the Trillium Compact as we derived it with RespGen.
- Determining the instrument response of a new sensor
- Confirming the instrument response you have calculated for a new sensor
- Confirming the nominal instrument response provided by the instrument manufacturer is as advertised in the IRIS Nominal Response Library
- Identifying mechanical failures
- Identifying phase (polarity) and gain problems
- Monitoring the instrument responses of seismic instrumentation in your network or pool of campaign instrumentation
- Something a little more extreme: You just returned from a campaign study in the Aleutians. Your Nanometrics Trillium Compact was thrown from a helicopter, banged around in your backpack for a day, was attacked by bears while you cowered in your tent hoping your deodorant did not attract the cubs, then it sat around covered in a meter of slush for a few months only to then suffer through a weeks-long journey on the barge you hitchhiked back to the mainland on. Now you are back in the lab and you want to make sure things are working.
Advantage over the Calibration Table or Coil
With the RespGen program is that you can confirm the entire instrument response curve. This includes the sensitivity, high and low corner frequencies. But we also make a calibration table. Check it out here.
SEND US YOUR DATA and we will send you back an RESP, dataless formatted or inventory-xml response file!
Acknowledgements: Many thanks to Professor Pavlis for his guidance and our friend Adam Ringler at the Albuquerque Seismological Laboratory (ASL) for his readiness to answer our questions and talk instrumentation.