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DATA QC - SOME IDEAS FOR IMPROVEMENT


These are just some notes for future consideration.

1 SEEDLINK DATA LATENCY MONITOR


1.1 Standard version


The normal Seedlink Monitor is part of the SeisComp package. We are using the Seedlink Server so it should not be too difficult to get the monitor program running.

The normal monitor web interface looks like this - clik to visit Geofon site:

Click to see large version.
Example of Geofon network Seedlink Monitor. Click image for large version.

1.2 Enhanced version


New features can be added:

  • Enable/disable alarm on individual stations
  • Set latency alarm limit
  • Select alarm sound - no need to monitor the computer screen - the machine will notify you if anything is wrong
  • Color coding of alarm status

Here's a working prototype made by O.M. as an AJAX exercise. It's using static sample data: OBSOLETE

Click to visit enhanced Seedlink Monitor
Enhanced Seedlink Server Monitor - click to see demo web page (using static data). OBSOLETE

1.3 References


2 PQLX (PASSCAL Quick Look eXtended)


PQLX website.

Quoting from http://www.iris.edu/software/pqlx/ :

PQLX (PASSCAL Quick Look eXtended) is open-source software authored by Richard Boaz (Boaz Consultancy) for evaluating seismic station performance and data quality. The software primarily consists of a server and client but also includes data extraction and migration tools. Given waveform data and instrument response files, PQLX server calculates trace statistics, Power Spectral Densities (PSD), and Probability Density Functions (PDF) and writes the results to a MySQL database for quick access.

Background information: PQLX, A Data Quality Control System: Uses and Applications, Orfeus Newsletter, June 2008

Plots can be based on weekly, monthly and yearly data.

The theory behind PQLX is not trivial, but interpretation of results are easier and would be of great benefit.

2.1 Standard PQLX


Example plot from USGS website:


Example of PQLX plot

2.2 Detecting errors in response files


These examples, and text, from PPT PQLX presentation (copy here).

Acc instead of velocity
Acc instead of velocity

"Acc instead of velocity, results in tilted PSD: Low Amps at Low Period, High Amps at High Period"

Corrected response

Corrected response.

Displacement instead of velocity
Displacement instead of velocity

"Displacement instead of velocity, results in tilted PSD: High Amps at Low Period, Low Amps at High Period"

Corrected response

Corrected response.

Gain error
Bad STS2 gain

"Bad STS2 gain, used 20.000 counts/volt instead of 1500 counts/volt, resulting in low corrected amplityde across spectrum."

Corrected response

Corrected response.

2.3 Effects of improved sensor thermal insulation


As shown in IberArray PPT presentation at Seisan Workshop Oct 2008, University of Bergen, Norway (copy here):

Effect of wrapping blanket around sensor.
Effect of improved sensor thermal insulation.

2.4 Seasonal and Diurnal Variations


Related to the PQLX are plots of seasonal and daily variations in data (source: http://geohazards.cr.usgs.gov/staffweb/mcnamara/PDF_PLOTS):

KONO seasonal

KONO seasonal PDF

KONO daily

KONO diurnal (daily) PDF - cultural noise, starting in the morning, can be seen.

2.5 How others are using PQLX


3 SPECTRUM AND AMPLITUDE OVER 10-MINUTE INTERVALS


In New Zealand, GeoNet is established as a collaboration between the Earthquake Commission and GNS Science to monitor four different types of geohazards: Earthquakes, landslides, tsunamis and volcanos. The latter uses some interesting displays to visualize data, called "RSAM" (Real-time Seismic-Amplitude Measurement) and "SSAM" (Seismic Spectral-Amplitude Measurement), explained here.

4 WEB-BASED "APP" - SOME IDEAS


HTML5 with new Canvas element makes real-time charting of data easier:

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Page last modified on February 10, 2019, at 10:59 AM
Electronics workshop
Department of Earth Science - University of Bergen
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