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Monitoring Seismic Velocity Changes Across the San Jacinto Fault Using Train-Generated Seismic Tremors.
Y Sheng1, A Mordret1, K Sager2
1University Grenoble Alpes University Savoie Mont Blanc CNRS IRD University Gustave Eiffel Grenoble France.
Geophysical Research Letters
|December 30, 2022
Summary
Freight train seismic tremors reveal high-frequency body waves for precise crustal monitoring. A 10-year study detected a slow-slip event on the San Jacinto Fault, potentially increasing major earthquake risk.
Area of Science:
- Geophysics
- Seismology
- Tectonics
Background:
- Traditional microseismic noise monitoring uses low-frequency surface waves, limiting detection of small tectonic changes.
- High-frequency body waves are ideal for detailed crustal studies but are difficult to isolate from ambient noise.
Purpose of the Study:
- To extract stable, high-frequency body waves from freight train seismic tremors for enhanced crustal velocity monitoring.
- To analyze 10 years of seismic velocity data at the San Jacinto Fault to detect and characterize tectonic events.
Main Methods:
- Utilized seismic tremors generated by freight trains as a source for high-frequency body wave analysis.
- Applied advanced signal processing to isolate body waves from surface waves and other noise.
- Analyzed a decade of seismic velocity data to map temporal and spatial changes in the San Jacinto Fault zone.
Main Results:
- Successfully extracted stable, high-frequency body waves, enabling high-resolution monitoring of crustal velocity perturbations.
- Identified and mapped a two-month-long episode of complex seismic velocity changes at the San Jacinto Fault.
- Interpreted these velocity changes as a previously undocumented slow-slip event on a locked fault segment.
Conclusions:
- Freight train seismic tremors provide a viable method for high-frequency seismic velocity monitoring.
- The detected slow-slip event has implications for understanding fault behavior and seismic hazard.
- This event may increase stress on surrounding fault sections, potentially contributing to a future major earthquake.
Keywords:
Anza seismic gapbody‐wave correlation functionshidden slow‐slip eventlong‐base seismic interferometrytrain‐generated seismic energyMore Related Videos
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