Seismic Network Operations

IC LSA

Tibet, China

IC LSA commences operations on: 1995,215

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Host: Institute of Geophysics and China Earthquake Administration
Latitude: 29.703
Longitude: 91.127
Elevation: 3660
Datalogger: Q330
Broadband: STS-1V/VBB
Accelerometer: FBA-23
Telemetry Status at the NEIC: Last Data In Less Than 10 Minutes
Station Photo Station Photo Station Photo 

Vault Condition: Seismometers' vault is located in a tunnel dug into a hillside. The seismometers are located on concrete piers which are attached to bedrock. The temperature is stable, but dehumidifiers are in operation.

Site Geology: Rock is Granite.

Location CodeChannel CodeInstrumentFlagsSample RateDipAzimuthDepth
00VMZStreckeisen STS-1VBB w/E300CH0.100.000.0015.00
00VM2Streckeisen STS-1VBB w/E300CH0.100.000.0015.00
00VM1Streckeisen STS-1VBB w/E300CH0.100.000.0015.00
00VHZStreckeisen STS-1VBB w/E300CG0.10-90.000.0015.00
00VH2Streckeisen STS-1VBB w/E300CG0.100.0090.0015.00
00VH1Streckeisen STS-1VBB w/E300CG0.100.000.0015.00
00LHZStreckeisen STS-1VBB w/E300CG1.00-90.000.0015.00
00LH2Streckeisen STS-1VBB w/E300CG1.000.0090.0015.00
00LH1Streckeisen STS-1VBB w/E300CG1.000.000.0015.00
00BHZStreckeisen STS-1VBB w/E300CG20.00-90.000.0015.00
00BH2Streckeisen STS-1VBB w/E300CG20.000.0090.0015.00
00BH1Streckeisen STS-1VBB w/E300CG20.000.000.0015.00
10VMWStreckeisen STS-2.5CH0.100.000.0015.00
10VMVStreckeisen STS-2.5CH0.100.000.0015.00
10VMUStreckeisen STS-2.5CH0.100.000.0015.00
10VHZStreckeisen STS-2.5CG0.10-90.000.0015.00
10VH2Streckeisen STS-2.5CG0.100.0090.0015.00
10VH1Streckeisen STS-2.5CG0.100.000.0015.00
10LHZStreckeisen STS-2.5CG1.00-90.000.0015.00
10LH2Streckeisen STS-2.5CG1.000.0090.0015.00
10LH1Streckeisen STS-2.5CG1.000.000.0015.00
10HHZStreckeisen STS-2.5CG100.00-90.000.0015.00
10HH2Streckeisen STS-2.5CG100.000.0090.0015.00
10HH1Streckeisen STS-2.5CG100.000.000.0015.00
20LNZKinemetrics FBA ES-T EpiSensor AccelerometerCG1.00-90.000.0015.00
20LN2Kinemetrics FBA ES-T EpiSensor AccelerometerCG1.000.0090.0015.00
20LN1Kinemetrics FBA ES-T EpiSensor AccelerometerCG1.000.000.0015.00
20HNZKinemetrics FBA ES-T EpiSensor AccelerometerTG200.00-90.000.0015.00
20HN2Kinemetrics FBA ES-T EpiSensor AccelerometerTG200.000.0090.0015.00
20HN1Kinemetrics FBA ES-T EpiSensor AccelerometerTG200.000.000.0015.00
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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
00BHZ2014:1432013:129 to No Ending TimeA0.0166450.0125310.128570.20203STS1VBBE3Random
  1. 2013-05-09
    Upgraded to Q330. Added STS-2.5 as secondary sensor. The STS-1 E channelwas previously very noisy. There were also previously sensitivity issues between the STS-1 and STS-2 that may have been humidity related.