Engineering summary
Dense seismic networks confuse SeisComP's autopicker and locator. This guide lists the symptoms and the configuration, filtering and manual-picking fixes that resolve them.
In short: In a SeisComP closely spaced network, the usual problems are P-phases picked but no S-phases, picks that differ by milliseconds between stations, P-picks starting after the first arrival and 'solution did not converge' or 'data is insufficient' errors during association. Fixes include verifying station coordinates, lowering picker amplitude thresholds, widening the picking window, filtering for signal-to-noise, cross-correlating picks and supplying a rough initial location before reducing residuals.
If you’re working with a closely spaced network of seismic stations and experiencing issues with Seiscomp, you’re not alone. Many seismologists face similar challenges when configuring Seiscomp for networks with high station density. In this blog post, we’ll discuss common issues and offer practical solutions to optimize Seiscomp’s performance.
Common Issues Observed in Seiscomp with Closely Spaced Networks
Seiscomp Autopick Limitations:
- P-Phases Detected but Not S-Phases: The autopicker successfully detects P-phases but fails to pick up S-phases or other phases.
- Minor Timing Differences: Picked phases at each station differ by only a few milliseconds.
- High Amplitude P-Picks: The P-picks start from a much higher amplitude instead of the first arrival.
- Lack of Automatic Phase Association: When manually associating P-phases, errors like “solution did not converge” or “data is insufficient” are encountered.
- Inactive Picker Button: Manual picking is restricted as the picker button remains inactive without phase association.
Challenges in Event Location:
- Manual Phase Association: Providing a rough nearby event location and time sometimes enables phase association, but errors persist.
- Imprecise Event Location: Even with phase association, the event location is not precise, and residuals need to be reduced for better accuracy.
Solutions and Recommendations
To address these issues, consider the following strategies:
Network Configuration:
- Verify Station Coordinates: Double-check that all station coordinates are accurate and correctly configured in Seiscomp.
- Adjust Network Parameters: Fine-tune the network parameters in Seiscomp to better accommodate the closely spaced stations.
Phase Picking and Association:
- Adjust Picking Parameters: Modify the picking parameters to be more sensitive to lower amplitude P-wave arrivals. This involves tweaking the configuration files, particularly focusing on thresholds and filters used for phase detection.
- Increase Picking Window: Expand the picking window to ensure that S-phases and other phases are detected.
- Cross-Correlation: Implement cross-correlation techniques to improve the consistency of phase picks across the closely spaced stations.
Data Quality and Preprocessing:
- Signal-to-Noise Ratio: Evaluate the signal-to-noise ratio for each station. High noise levels can impede accurate phase picking.
- Filtering: Apply suitable filters to the data to enhance the P- and S-phase arrivals.
- Amplitude Thresholds: Adjust the amplitude thresholds for phase picking to ensure the picks start from the first arrival rather than higher amplitudes.
Manual Adjustments and Event Location:
- Initial Rough Location: Provide an initial rough event location and time to aid the process. Ensure the parameters are as accurate as possible.
- Reduce Residuals: Manually adjust picks after initial phase association to reduce residuals and improve event location accuracy.
- Review and Pick Additional Phases: Manually review the data to pick additional phases that the automatic picker might have missed. This can enhance overall phase association and event location precision.
Algorithm and Software Configuration:
- Review Configuration Files: Thoroughly review and adjust Seiscomp’s configuration files, optimizing them for closely spaced networks.
- Consult Documentation: Refer to Seiscomp’s documentation and community forums for specific parameters and settings that can improve performance for closely spaced networks.
Troubleshooting Errors:
- Solution Did Not Converge: This error might indicate issues with initial parameters or insufficient data quality. Ensuring high-quality data and accurate initial parameters can help.
- Data is Insufficient: Confirm that there is adequate data coverage and that all stations are operational and correctly configured.
By systematically addressing these aspects, you can improve Seiscomp’s performance with your closely spaced network and achieve more accurate phase picking and event locations.
About QuakeLogic
QuakeLogic is a leading provider of advanced seismic monitoring solutions, offering a range of products and services designed to enhance the accuracy and efficiency of seismic data acquisition and analysis. Our innovative technologies and expert support help organizations worldwide to better understand and mitigate the impacts of seismic events.
Contact Information:
- Email: sales@quakelogic.net
- Phone: +1-916-899-0391
- WhatsApp: +1-650-353-8627
- Website: www.quakelogic.net
For more information about our products and services, please visit our website or contact our sales team. We are here to help you with all your seismic monitoring needs.
Thank you for choosing QuakeLogic. We look forward to assisting you with your seismic monitoring projects.
Key Takeaways
- Symptoms: P-phases detected without S-phases, picks only milliseconds apart, P-picks beginning at high amplitude rather than first arrival.
- Association errors 'solution did not converge' and 'data is insufficient' usually point to poor initial parameters or inadequate data quality.
- Lower amplitude thresholds and tune filters in the picker configuration so picks begin at the true first arrival.
- Expand the picking window and use cross-correlation to make S-phase picks consistent across closely spaced stations.
- Provide a rough initial event location and time, then manually adjust picks to reduce residuals and improve the location.
Frequently Asked Questions
On a closely spaced network SeisComP's autopicker often detects P-phases but misses S-phases because the default picking window and thresholds are tuned for wider station spacing. Expanding the picking window, adjusting amplitude thresholds and filters, and applying cross-correlation across neighboring stations improves S-phase detection and makes picks consistent, which in turn lets phase association proceed.
The 'solution did not converge' error in SeisComP usually indicates poor initial parameters or insufficient data quality. Verify station coordinates, supply a rough initial event location and origin time, make sure enough stations are operational with adequate signal-to-noise ratio, then manually adjust picks after initial association to reduce residuals. Picking additional phases the autopicker missed also helps the locator converge.
P-picks that start late at high amplitude happen when the picker's amplitude threshold is set too high for the recorded signals. Lower the amplitude thresholds and refine the filters in the picking configuration so the detector is sensitive to the lower-amplitude first arrival. Evaluating signal-to-noise ratio per station and applying suitable filtering before picking also moves picks back to the true onset.
In SeisComP the manual picker button remains inactive until phases have been associated with an event. If automatic association fails on a closely spaced network, providing a rough nearby event location and time can enable association, after which manual picking becomes available. Verifying station coordinates and network parameters first removes a common cause of failed association.
To improve SeisComP event locations in a closely spaced network, start from accurate station coordinates, provide a good initial location and time, review the data to pick additional P and S phases the autopicker missed, and manually adjust picks to reduce residuals. Fine-tuning network parameters and reviewing SeisComP's configuration files and documentation for dense-network settings further tightens the solution.
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Topic cluster
Related engineering knowledge areas
- Earthquake EngineeringSeismic hazard, ground motion, structural response, fragility, and resilience guidance.
- Structural Health MonitoringMonitoring for bridges, buildings, dams, tunnels, industrial facilities, and resilient infrastructure.
- Earthquake Early WarningOn-site detection, alerting workflows, seismic switches, and critical infrastructure warning systems.
- Infrasound MonitoringLow-frequency acoustic sensing for environmental noise, blast, UAV, volcano, and defense applications.
Definitions and references
Terms, standards, and source cues
- seismic hazard: related to Earthquake Engineering in this QuakeLogic knowledge cluster.
- ground motion: related to Earthquake Engineering in this QuakeLogic knowledge cluster.
- SHM: related to Structural Health Monitoring in this QuakeLogic knowledge cluster.
- damage detection: related to Structural Health Monitoring in this QuakeLogic knowledge cluster.
- earthquake early warning: related to Earthquake Early Warning in this QuakeLogic knowledge cluster.
- seismic switch: related to Earthquake Early Warning in this QuakeLogic knowledge cluster.
- infrasound sensors: related to Infrasound Monitoring in this QuakeLogic knowledge cluster.
- low-frequency noise: related to Infrasound Monitoring in this QuakeLogic knowledge cluster.
Standards mentioned
- SeisComP documentation and configuration references
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