Seismic Network Operations

IU KOWA

Kowa, Mali

IU KOWA commences operations on: 1998,067

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Host: National Center for Science and Technology Research
Latitude: 14.497
Longitude: -4.014
Elevation: 321
Datalogger: Q330
Broadband: STS-2_High-gain
Accelerometer: FBA_ES-T_EpiSensor_Accelerometer
Telemetry Status at the NEIC: No Data In More Than 24 Hours
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Site Description: Located in the Niger River delta region of the Sahara desert in Mali continent of Africa. KOWA operates as a remote IRIS2 station with the data processor operating at the airport in Sevare and the acquisition unit operating at the Dogon village of Kowa approximately 10k from Sevare. The site uses radio modems for data transmission and solar power. A dialup modem is operational. Internet access is not available at this time. National language is French with 75% of the poulation speaking Bambara.

Vault Condition: 40 meter horizontal tunnel with approx. 10-15 meters of overburden. (solid rock), *Dry and very hot

Site Geology: Sandstone

Location CodeChannel CodeInstrumentFlagsSample RateDipAzimuthDepth
30LDOCI/PAS pressure sensorCW1.000.000.005.00
20LNZFBA ES-T EpiSensor AccelerometerCG1.00-90.000.005.00
20LN1FBA ES-T EpiSensor AccelerometerCG1.000.000.005.00
20HNZFBA ES-T EpiSensor AccelerometerTG100.00-90.000.005.00
20HN1FBA ES-T EpiSensor AccelerometerTG100.000.000.005.00
10VHZTrillium 240 broad bandCG0.10-90.000.005.00
10VH1Trillium 240 broad bandCG0.100.000.005.00
10HH1Trillium 240 broad bandTG100.000.000.005.00
10BHZTrillium 240 broad bandCG40.00-90.000.005.00
10LHZTrillium 240 broad bandCG1.00-90.000.005.00
10LH1Trillium 240 broad bandCG1.000.000.005.00
10HHZTrillium 240 broad bandTG100.00-90.000.005.00
10BH1Trillium 240 broad bandCG40.000.000.005.00
00VHZSTS-2 High-gainCG0.10-90.000.005.00
00VH1STS-2 High-gainCG0.100.000.005.00
00LHZSTS-2 High-gainCG1.00-90.000.005.00
00LH1STS-2 High-gainCG1.000.000.005.00
00HHZSTS-2 High-gainTG100.00-90.000.005.00
00HH1STS-2 High-gainTG100.000.000.005.00
00BHZSTS-2 High-gainCG40.00-90.000.005.00
00BH1STS-2 High-gainCG40.000.000.005.00
20LN2FBA ES-T EpiSensor AccelerometerCG1.000.0090.005.00
20HN2FBA ES-T EpiSensor AccelerometerTG100.000.0090.005.00
10VH2Trillium 240 broad bandCG0.100.0090.005.00
10LH2Trillium 240 broad bandCG1.000.0090.005.00
10HH2Trillium 240 broad bandTG100.000.0090.005.00
10BH2Trillium 240 broad bandCG40.000.0090.005.00
00VH2STS-2 High-gainCG0.100.0090.005.00
00LH2STS-2 High-gainCG1.000.0090.005.00
00HH2STS-2 High-gainTG100.000.0090.005.00
00BH2STS-2 High-gainCG40.000.0090.005.00
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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
00BHZ2011:148 2011:147 to No Ending TA0.0138270.0122690.070480.076279 STS-2-HGRandom
10BHZ2011:149 2011:147 to No Ending TA0.014360.00769990.104320.088975 TR240Random
  1. Current Issues
    Since Aug. 12 (2012) timing quality has been bad. Telemetry has stopped possibly due to power problems.
  2. 2011-11-05
    Power system repaired and data flow has resumed.
  3. 2011-06-11
    Data flow stopped due to power system failure.
  4. 2011-05-25
    Upgraded to Q330 digitizer.