Seismic Network Operations

IU AFI

Afiamalu, Samoa

IU AFI commences operations on: 1993,236

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Host: Ministry of Natural Resources and Environment
Latitude: -13.909
Longitude: -171.777
Elevation: 706
Datalogger: Q330
Broadband: STS-1VBB_w/E300
Accelerometer: FBA_ES-T_EpiSensor_Accelerometer
Telemetry Status at the NEIC: Last Data In Less Than 24 Hours And More Than 10 Minutes
Station Photo Station Photo Station Photo 

Vault Condition: Vault is a small concrete block building set into the ground so that the roof is at ground level. The sides are filled in with dirt. The floor is basalt bedrock. Piers are not isolated from the floor. A dehumidifier is normally in operation.

Site Geology: Pleistocene Salani Volcanics.

Location CodeChannel CodeInstrumentFlagsSample RateDipAzimuthDepth
50LWSVaisala Weather TransmitterCW1.000.000.000.00
50LWDVaisala Weather TransmitterCW1.000.000.000.00
50LRIVaisala Weather TransmitterCW1.000.000.000.00
50LRHVaisala Weather TransmitterCW1.000.000.000.00
50LKOVaisala Weather TransmitterCW1.000.000.000.00
50LIOVaisala Weather TransmitterCW1.000.000.000.00
50LDOVaisala Weather TransmitterCW1.000.000.000.00
31LDOCI/PAS pressure sensorCW1.000.000.000.00
20HNZKinemetrics FBA ES-T EpiSensor AccelerometerTG100.00-90.000.001.00
20HN2Kinemetrics FBA ES-T EpiSensor AccelerometerTG100.000.0090.001.00
20LNZKinemetrics FBA ES-T EpiSensor AccelerometerCG1.00-90.000.001.00
20LN2Kinemetrics FBA ES-T EpiSensor AccelerometerCG1.000.0090.001.00
20LN1Kinemetrics FBA ES-T EpiSensor AccelerometerCG1.000.000.001.00
20HN1Kinemetrics FBA ES-T EpiSensor AccelerometerTG100.000.000.001.00
10VMWStreckeisen STS-2.5CH0.100.000.001.00
10VMVStreckeisen STS-2.5CH0.100.000.001.00
10VMUStreckeisen STS-2.5CH0.100.000.001.00
10VHZStreckeisen STS-2.5CG0.10-90.000.001.00
10VH2Streckeisen STS-2.5CG0.100.0090.001.00
10VH1Streckeisen STS-2.5CG0.100.000.001.00
10LHZStreckeisen STS-2.5CG1.00-90.000.001.00
10LH2Streckeisen STS-2.5CG1.000.0090.001.00
10LH1Streckeisen STS-2.5CG1.000.000.001.00
10HHZStreckeisen STS-2.5TG100.00-90.000.001.00
10HH2Streckeisen STS-2.5TG100.000.0090.001.00
10HH1Streckeisen STS-2.5TG100.000.000.001.00
10BHZStreckeisen STS-2.5CG40.00-90.000.001.00
10BH2Streckeisen STS-2.5CG40.000.0090.001.00
10BH1Streckeisen STS-2.5CG40.000.000.001.00
00VMZStreckeisen STS-1VBB w/E300CH0.100.000.001.00
00VM2Streckeisen STS-1VBB w/E300CH0.100.000.001.00
00VM1Streckeisen STS-1VBB w/E300CH0.100.000.001.00
00VHZStreckeisen STS-1VBB w/E300CG0.10-90.000.001.00
00VH2Streckeisen STS-1VBB w/E300CG0.100.0090.001.00
00VH1Streckeisen STS-1VBB w/E300CG0.100.000.001.00
00LHZStreckeisen STS-1VBB w/E300CG1.00-90.000.001.00
00LH2Streckeisen STS-1VBB w/E300CG1.000.0090.001.00
00LH1Streckeisen STS-1VBB w/E300CG1.000.000.001.00
00BHZStreckeisen STS-1VBB w/E300CG20.00-90.000.001.00
00BH2Streckeisen STS-1VBB w/E300CG20.000.0090.001.00
00BH1Streckeisen STS-1VBB w/E300CG20.000.000.001.00
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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
00BH12010:3572010:357 to presentA0.041220.031410.313930.35696STS1-VBBE3RANDOM
00BH22010:0592010:054 to presentA0.0160890.0108830.123420.11654STS1-VBBE3RANDOM
00BHZ2010:3572010:357 to presentA0.041220.029370.313930.35696STS1-VBBE3RANDOM
10BHZ2010:3572010:357 to presentA0.027780.016040.21250.21761STS-2-HGRANDOM
00BH22013:2142010:054 to No Ending TimeA0.0221850.00972360.136350.21784STS1VBBE3Random
00BHZ2013:2142010:357 to No Ending TimeA0.0163480.00921250.119990.17504STS1VBBE3Random
00BH12013:2142010:357 to No Ending TimeA0.0153260.0093010.124920.13697STS1VBBE3Random
  1. 2013-07-30
    System power and communications restored.
  2. 2012-12-13
    Station power was knocked out by a cyclone.
  3. 2010-02-28
    Upgraded to Q330 digitizer.