Seismic Network Operations

IU WAKE

Wake Island

IU WAKE commences operations on: 1997,126

Country Flag
Host: US Air Force
Latitude: 19.283
Longitude: 166.652
Elevation: 20
Datalogger: Q330
Broadband: KS-54000
Accelerometer: FBA_ES-T_EpiSensor_Accelerometer
Telemetry Status at the NEIC: Last Data In Less Than 10 Minutes
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Vault Condition: borehole and concrete pier

Site Geology: coral limestone

Location CodeChannel CodeInstrumentFlagsSample RateDipAzimuthDepth
30LDOCI/PAS pressure sensorCW1.000.000.000.00
20LNZFBA ES-T EpiSensor AccelerometerCG1.00-90.000.002.00
20LN2FBA ES-T EpiSensor AccelerometerCG1.000.0090.002.00
20LN1FBA ES-T EpiSensor AccelerometerCG1.000.000.002.00
20HNZFBA ES-T EpiSensor AccelerometerTG100.00-90.000.002.00
20HN2FBA ES-T EpiSensor AccelerometerTG100.000.0090.002.00
20HN1FBA ES-T EpiSensor AccelerometerTG100.000.000.002.00
00VHZKS-54000CG0.10-90.000.0081.50
00VH2KS-54000CG0.100.00250.0081.50
00VH1KS-54000CG0.100.00160.0081.50
00LHZKS-54000CG1.00-90.000.0081.50
00BH1KS-54000CG20.000.00160.0081.50
00LH2KS-54000CG1.000.00250.0081.50
00LH1KS-54000CG1.000.00160.0081.50
00BHZKS-54000CG20.00-90.000.0081.50
00BH2KS-54000CG20.000.00250.0081.50
10VHZSTS-2.5CG0.10-90.000.002.00
10VH2STS-2.5CG0.100.0090.002.00
10VH1STS-2.5CG0.100.000.002.00
10LHZSTS-2.5CG1.00-90.000.002.00
10LH2STS-2.5CG1.000.0090.002.00
10LH1STS-2.5CG1.000.000.002.00
10HHZSTS-2.5TG100.00-90.000.002.00
10HH2STS-2.5TG100.000.0090.002.00
10HH1STS-2.5TG100.000.000.002.00
10BHZSTS-2.5CG40.00-90.000.002.00
10BH2STS-2.5CG40.000.0090.002.00
10BH1STS-2.5CG40.000.000.002.00
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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
00BH12012:054 2009:131 to No Ending TA0.0172820.00624470.0767910.065681 54000Random
00BH22012:054 2009:131 to No Ending TA0.00622220.00620990.0646090.063525 54000Random
00BHZ2012:054 2009:131 to No Ending TA0.00618690.00610930.0663170.063549 54000Random
10BHZ2012:055 2009:131 to No Ending TA0.0310890.0142070.21760.086847 STS-2-HGRandom
  1. Current Issues
    The KS54000 continues to have high noise one the vertical channel despite work done to address this in March 2012. The newly installed episensor appears to have high noise on the LN2 channel.
  2. 2012-03-10
    The Episensor which had excessively noisy channels was replaced. The STS-2 was replaced with a STS-2.5.
  3. 2007-11-15
    Upgraded to Q330 digitizer.