Seismic Network Operations
IU JOHN
Johnston Island, USA
IU JOHN commences operations on: 1998,205
| Host: | US Fish and Wildlife Service |
|---|---|
| Latitude: | 16.733 |
| Longitude: | -169.529 |
| Elevation: | 2 |
| Datalogger: | Q330 |
| Broadband: | STS-2_Standard-gain |
| Accelerometer: | FBA_ES-T_EpiSensor_Accelerometer |
| Telemetry Status at the NEIC: |
 Last Data In Less Than 10 Minutes |
Site Description: Solar powered site in the middle of a 1/2 mile by 2 mile Pacific atoll.
Vault Condition: STS-2 and FBA-23 are located in a very shallow concrete vault. CMG3-T-B borehole depth is -8m.
Site Geology: Sandstone, basalt
| Location Code | Channel Code | Instrument | Flags | Sample Rate | Dip | Azimuth | Depth |
|---|---|---|---|---|---|---|---|
| 00 | VHZ | STS-2 Standard-gain | CG | 0.10 | -90.00 | 0.00 | 0.00 |
| 10 | VHZ | Trillium 240 broad band | CG | 0.10 | -90.00 | 0.00 | 0.00 |
| 00 | VH2 | STS-2 Standard-gain | CG | 0.10 | 0.00 | 90.00 | 0.00 |
| 10 | VH2 | Trillium 240 broad band | CG | 0.10 | 0.00 | 86.00 | 0.00 |
| 00 | VH1 | STS-2 Standard-gain | CG | 0.10 | 0.00 | 0.00 | 0.00 |
| 10 | VH1 | Trillium 240 broad band | CG | 0.10 | 0.00 | 356.00 | 0.00 |
| 20 | LNZ | FBA ES-T EpiSensor Accelerometer | CG | 1.00 | -90.00 | 0.00 | 0.00 |
| 20 | LN2 | FBA ES-T EpiSensor Accelerometer | CG | 1.00 | 0.00 | 90.00 | 0.00 |
| 20 | LN1 | FBA ES-T EpiSensor Accelerometer | CG | 1.00 | 0.00 | 0.00 | 0.00 |
| 00 | LHZ | STS-2 Standard-gain | CG | 1.00 | -90.00 | 0.00 | 0.00 |
| 10 | LHZ | Trillium 240 broad band | CG | 1.00 | -90.00 | 0.00 | 0.00 |
| 00 | LH2 | STS-2 Standard-gain | CG | 1.00 | 0.00 | 90.00 | 0.00 |
| 10 | LH2 | Trillium 240 broad band | CG | 1.00 | 0.00 | 86.00 | 0.00 |
| 00 | LH1 | STS-2 Standard-gain | CG | 1.00 | 0.00 | 0.00 | 0.00 |
| 10 | LH1 | Trillium 240 broad band | CG | 1.00 | 0.00 | 356.00 | 0.00 |
| 30 | LDO | CI/PAS pressure sensor | CW | 1.00 | 0.00 | 0.00 | 0.00 |
| 20 | HNZ | FBA ES-T EpiSensor Accelerometer | TG | 100.00 | -90.00 | 0.00 | 0.00 |
| 20 | HN2 | FBA ES-T EpiSensor Accelerometer | TG | 100.00 | 0.00 | 90.00 | 0.00 |
| 20 | HN1 | FBA ES-T EpiSensor Accelerometer | TG | 100.00 | 0.00 | 0.00 | 0.00 |
| 10 | HHZ | Trillium 240 broad band | TG | 100.00 | -90.00 | 0.00 | 0.00 |
| 10 | HH2 | Trillium 240 broad band | TG | 100.00 | 0.00 | 86.00 | 0.00 |
| 10 | HH1 | Trillium 240 broad band | TG | 100.00 | 0.00 | 356.00 | 0.00 |
| 00 | BHZ | STS-2 Standard-gain | CG | 40.00 | -90.00 | 0.00 | 0.00 |
| 10 | BHZ | Trillium 240 broad band | CG | 40.00 | -90.00 | 0.00 | 0.00 |
| 10 | BH2 | Trillium 240 broad band | CG | 40.00 | 0.00 | 86.00 | 0.00 |
| 00 | BH2 | STS-2 Standard-gain | CG | 40.00 | 0.00 | 90.00 | 0.00 |
| 10 | BH1 | Trillium 240 broad band | CG | 40.00 | 0.00 | 356.00 | 0.00 |
| 00 | BH1 | STS-2 Standard-gain | CG | 40.00 | 0.00 | 0.00 | 0.00 |
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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.
| Loc | Chan | Cal Date | Epoch-Span | Grade | Amp Nominal Error (dB) | Amp Best Fit Error (dB) | Phase Nominal Error (degree) | Phase Best Fit Error (degree) | Sensor | Cal Type |
|---|---|---|---|---|---|---|---|---|---|---|
| 10 | BHZ | 2010:310 | 2010:221 to No Ending T | A | 0.013528 | 0.0072217 | 0.10645 | 0.081076 | TR240 | Random |
| 00 | BHZ | 2010:309 | 2010:221 to No Ending T | A | 0.012746 | 0.012256 | 0.070532 | 0.068585 | STS-2-SG | Random |
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Current IssuesLNZ and LN1 channels appear to be bad.
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2010-08-10Upgraded to Q330 digitizer.
