Seismic Network Operations


College Outpost, Alaska, USA

IU COLA commences operations on: 1996,166

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Host: University of Alaska
Latitude: 64.874
Longitude: -147.862
Elevation: 200
Datalogger: Q330
Broadband: KS-54000
Accelerometer: FBA_ES-T_EpiSensor_Accelerometer
Telemetry Status at the NEIC: Last Data In Less Than 10 Minutes
Station Photo Station Photo Station Photo Station Photo 

Vault Condition: The surface vault is climate controlled. The concrete pier is isolated from the floor of the vault.

Site Geology: The borehole is drilled into approximately 50 meters of various types of silt and loess. A colluvium layer exists between approximately 55 and 61 meters. Beneath the colluvium to 102 meters there are various types of granitic rocks, from felsic granitic finely grained rock to, at deeper sections, a highly altered granite. From 103 meters to 122 meters lithologies range from phyllite to calc phillite to quartzite at the bottom of the borehole. The surface vault sits atop the silt and loess deposits.

Location CodeChannel CodeInstrumentFlagsSample RateDipAzimuthDepth
20LNZFBA ES-T EpiSensor AccelerometerCG1.00-
20LN2FBA ES-T EpiSensor AccelerometerCG1.000.0090.000.00
20LN1FBA ES-T EpiSensor AccelerometerCG1.
20HNZFBA ES-T EpiSensor AccelerometerTG100.00-
20HN2FBA ES-T EpiSensor AccelerometerTG100.000.0090.000.00
20HN1FBA ES-T EpiSensor AccelerometerTG100.
10VHZSTS-2 High-gainCG0.10-
10VH2STS-2 High-gainCG0.100.0092.000.00
10VH1STS-2 High-gainCG0.
10LHZSTS-2 High-gainCG1.00-
10LH2STS-2 High-gainCG1.000.0092.000.00
10LH1STS-2 High-gainCG1.
10HHZSTS-2 High-gainTG100.00-
10HH2STS-2 High-gainTG100.000.0092.000.00
10HH1STS-2 High-gainTG100.
10BHZSTS-2 High-gainCG40.00-
10BH2STS-2 High-gainCG40.000.0092.000.00
10BH1STS-2 High-gainCG40.
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As part of the annual calibration process, the USGS runs a sequence that includes a random, a step, and several sine wave calibrations.  The USGS analyzes the random binary calibration signal in order to estimate the instrument response.  The figures below show the results from the analysis of the most recent processed calibration at the station.

We use an iterative three-step method to estimate instrument response parameters (poles, zeros, sensitivity and gain) and their associated errors using random calibration signals. First, we solve a coarse non-linear inverse problem using a least squares grid search to yield a first approximation to the solution. This approach reduces the likelihood of poorly estimated parameters (a local-minimum solution) caused by noise in the calibration records and enhances algorithm convergence. Second, we iteratively solve a non-linear parameter estimation problem to obtain the least squares best-fit Laplace pole/zero/gain model. Third, by applying the central limit theorem we estimate the errors in this pole/zero model by solving the inverse problem at each frequency in a 2/3rds-octave band centered at each best-fit pole/zero frequency. This procedure yields error estimates of the 99% confidence interval.

LocChanCal DateEpoch-SpanGradeAmp Nominal Error (dB)Amp Best Fit Error (dB)Phase Nominal Error (degree)Phase Best Fit Error (degree)SensorCal Type
00BHZ2012:032 2011:026 to No Ending TiA0.0277340.00660690.0803470.11102 54000Random
00BH22012:032 2011:026 to No Ending TiA0.0584290.011670.134890.26067 54000Random
00BH12012:032 2011:026 to No Ending TiA0.00740550.00499540.0591530.050355 54000Random
10BHZ2012:033 2011:027 to No Ending TiA0.015450.0142180.122420.11671 STS-2-HGRandom
  1. 2012-09-24
    The KS54000 was replaced due to failure of multiple components.
  2. 2012-04-10
    Episensor replaced due to noise issues.
  3. 2009-07-09
    Upgraded to Q330 digitizer.