Seismic Network Operations


Pohakuloa, Hawaii, USA

IU POHA commences operations on: 1999,317

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Host: US Army
Latitude: 19.757
Longitude: -155.533
Elevation: 1990
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: N/A, KS54000 borehole depth is -80.3m.

Site Geology: basalt

Location CodeChannel CodeInstrumentFlagsSample RateDipAzimuthDepth
20LN2FBA ES-T EpiSensor AccelerometerCG1.000.0090.000.00
20HN2FBA ES-T EpiSensor AccelerometerTG100.000.0090.000.00
10VH2STS-2 High-gainCG0.100.0090.000.00
10LH2STS-2 High-gainCG1.000.0090.000.00
10HH2STS-2 High-gainTG100.000.0090.000.00
10BH2STS-2 High-gainCG40.000.0090.000.00
30LDOCI/PAS pressure sensorCW1.
20LNZFBA ES-T EpiSensor AccelerometerCG1.00-
20LN1FBA ES-T EpiSensor AccelerometerCG1.
20HNZFBA ES-T EpiSensor AccelerometerTG100.00-
20HN1FBA ES-T EpiSensor AccelerometerTG100.
10VHZSTS-2 High-gainCG0.10-
10VH1STS-2 High-gainCG0.
10LHZSTS-2 High-gainCG1.00-
10LH1STS-2 High-gainCG1.
10HHZSTS-2 High-gainTG100.00-
10HH1STS-2 High-gainTG100.
10BHZSTS-2 High-gainCG40.00-
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
10BHZ2011:218 2011:020 to No Ending TA0.0146920.0151090.0829630.080041 STS-2-HGRandom
00BHZ2011:217 2011:020 to No Ending TA0.0208070.00615010.0764070.081593 54000Random
00BH22011:217 2011:020 to No Ending TA0.00824620.00548650.0636220.052712 54000Random
00BH12011:217 2011:020 to No Ending TA0.0283450.00697770.0829460.10513 54000Random
  1. 2012-03-05
    The Episensor which had excessively noisy channels was replaced.
  2. 2011-01-20
    Upgraded to Q330 digitizer.