Seismic Instrumentation Albuquerque Seismological Laboratory Seismometer and Accelerometer Testing Bob Hutt, Adam Ringler, John Evans June 10-11, 2013 Seismic Instrumentation Technology Symposium

ASL Location on Isleta Reservation near Kirtland AFB June 10-11, 2013 Seismic Instrumentation Technology Symposium

Seismic Instrumentation Albuquerque Seismological Laboratory: Originally a Seismometer Test Facility Seismometer Test Facility Needed to support the World Wide Standardized Seismograph Network (WWSSN) Quiet site sought: Low noise at 1 Hz Nationwide noise survey conducted in 1959 Jim Devine and Joji Tomei Baby Benioff and photographic drum recorder Quietest site found was near Grants, NM Isleta site noise nearly same as Grants site Isleta site chosen due to proximity of ABQ airport and to minimize dealing with military bureaucracy June 10-11, 2013 Seismic Instrumentation Technology Symposium

Seismometer and Data Acquisition System Evaluation Seismometer Evaluation Dynamic range Noise (side-by-side comparison in quiet vault or borehole) Linearity Clip level Accurate transfer function determination Determination of sensitive axis (accurate orientation), cross-axis coupling Other tests: Described in Hutt, C. R., Evans, J. R., Followill, F., Nigbor, R.L., and Wielandt, E.: Guidelines for Standardized Testing of Broadband Seismometers and Accelerometers, USGS Open File Report 2009-1295. Data Acquisition System Evaluation Dynamic range, clip level, linearity, sensitivity, crosstalk, common mode rejection, etc. Cooperation with Sandia National Laboratory June 10-11, 2013 Seismic Instrumentation Technology Symposium

BB Seismometer noise test Three BB seismometers on slab with reference instruments Sleeman 3-sensor (or Holcomb 2-sensor) coherence analysis used to determine instrument noise that is below ambient background noise June 10-11, 2013 Seismic Instrumentation Technology Symposium

Seismic Instrumentation Examples of noise of three sensors determined with Sleeman multi-channel coherence analysis Higher noise example. Higher apparent noise in microseism band caused by imperfect axis alignment between sensors. Low noise example June 10-11, 2013 Seismic Instrumentation Technology Symposium

Comparison of Holcomb (2-sensor) to Sleeman (multi-sensor) noise levels 9/23/2018

VBB seismometer noise as judged by ability to observe signals Here, both instruments resolve modes well. In this case, one instrument (blue) has higher noise than the other in the mode band. June 10-11, 2013 Seismic Instrumentation Technology Symposium

Noise correlated with atmospheric pressure changes Top trace is air pressure Bottom four traces are horizontal long period data from two VBB instruments under test. High correlation with top trace is due to baseplate warping in response to air pressure changes. June 10-11, 2013 Seismic Instrumentation Technology Symposium

Example of direct noise determination for strong motion accelerometers Instrument noise of most strong motion sensors is above background noise, so may be observed directly. (Coherence analysis is not required.) June 10-11, 2013 Seismic Instrumentation Technology Symposium

Example of higher than normal noise from a strong motion instrument Z component has step offsets NS component normal EW component has excessive noise level June 10-11, 2013 Seismic Instrumentation Technology Symposium

Seismic Instrumentation Frequency response of VBB instrument by driving calibration coil with random signal Example of a bad STS-1 response (probably caused by high humidity inside sensor) Example of a good amplitude & phase response of STS-1 June 10-11, 2013 Seismic Instrumentation Technology Symposium

Mid-band sensitivity verified by comparing response-corrected PSDs PSD of instrument under test (green) matches reference instruments (blue and red) in 6-second microseism band June 10-11, 2013 Seismic Instrumentation Technology Symposium

Borehole test facilities: Depths range from 3m to 200m PVC-cased shallow holes, 3m to 10m, in soil. IRIs-funded, used mainly for testing posthole installation techniques for TA. Two deeper (30m and 60m) steel cased holes in background (in granite). Allan Sauter working in instrumentation pit near shallow holes. June 10-11, 2013 Seismic Instrumentation Technology Symposium

Shake tables and step calibration table Left: Erhard Wielandt checking cross-axis coupling with horizontal shake table. Below: Erhard using step calibration table (table is his design). June 10-11, 2013 Seismic Instrumentation Technology Symposium

DC sensitivity of accelerometers determined by box flip test June 10-11, 2013 Seismic Instrumentation Technology Symposium

Example of results of box flip tests for some MEMS accelerometers Results are sensitivity, polarity, offset, and orientation of each axis June 10-11, 2013 Seismic Instrumentation Technology Symposium

Seismic Instrumentation ASL Test Facilities Please see Adam Ringler’s poster for more details June 10-11, 2013 Seismic Instrumentation Technology Symposium

Seismic Instrumentation Come see us! ASL’s 50th Anniversary, June 2011 June 10-11, 2013 Seismic Instrumentation Technology Symposium

Seismic Instrumentation References & Publications See also http://earthquake.usgs.gov/regional/asl/pubs/ Ringler, A. T. and C. R. Hutt (2012). Examples of Guidelines for Seismometer Testing: Weak motion broadband, in prep. Ringler, A. T., C. R. Hutt, and K. Persefield (2012). Seismic station installation orientation errors at ANSS and IRIS/USGS stations, Seis. Res. Lett., in prep. Ringler, A. T., L. S. Gee, B. Marshall, C. R. Hutt, and T. Storm (2012). Data quality of seismic records from the Tohoku, Japan, earthquake as recorded across the Albuquerque Seismological Laboratory networks, Seis. Res. Lett., 83 (3), 575-584. Ringler, A. T., J. D. Edwards, C. R. Hutt, and F. Shelly (2012). Relative azimuth inversion by way of damped maximum correlation estimates, Comp. and Geosci.,43, 1-6. Ringler, A. T., C. R. Hutt, R. Aster, H. Bolton, L. S. Gee, and T. Strom (2012). Estimating pole-zero errors in GSN-IRIS/USGS network calibration metadata, Bull. Seis. Soc. Amer., 102 (2), 836-841. Hutt, C. R., J. Peterson, L. Gee, J. Derr, A. Ringler, and D. Wilson (2011). Albuquerque Seismological Laboratory--50 years of global seismology. U.S. Geological Survey Fact Sheet, 2011-3065, 4 p. Ringler, A. T., C. R. Hutt, J. R. Evans, and L. D. Sandoval (2011). A Comparison of seismic instrument self-noise analysis techniques, Bull. Seis. Soc. Amer., 101 (2), 558-567. June 10-11, 2013 Seismic Instrumentation Technology Symposium

References & Publications (cont.) Hutt, C. R. and A. T. Ringler (2011). Some possible causes of and corrections for STS-1 response changes in the Global Seismographic Network, Seis. Res. Lett., 82 (4), 560-571. Ringler, A. T. and C. R. Hutt (2011). Self-noise models of seismic instruments, Seis. Res. Lett., 81 (6), 972-983. McNamara, D. E., A. T. Ringler, C. R. Hutt, and L. S. Gee (2011), Seismically observed seiching in the Panama Canal, J. Geophys. Res., 116, B04312, doi:10.1029/2010JB007930. Ringler, A. T., L. S. Gee, C. R. Hutt, and D. E. McNamara (2010). Temporal variations in global seismic station ambient noise power levels, Seis. Res. Lett., 81 (4), 605-613. Evans, J. R., F. Followill, C. R. Hutt, R. P. Kromer, R. L. Nigbor, A. T. Ringler, J. M. Steim, and E. Wielandt (2010). Method for calculating self-noise spectra and operating ranges for seismographic inertial sensors and recorders, Seis. Res. Lett., 81 (4), 640-646. Hutt, C. R. and A. T. Ringler (2009). Causes and corrections for STS-1 gain changes in the Global Seismographic Network, Eos. Trans. AGU, 90 (52), Fall Meet. Suppl., Abstract S23A-1735. Ringler, A. T. and C. R. Hutt (2009). Self-noise models of seismic instruments, Eos. Trans. AGU, 90 (52), Fall Meet. Suppl., Abstract S23A-1736. June 10-11, 2013 Seismic Instrumentation Technology Symposium