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Creep fronts and complexity in laboratory earthquake sequences illuminate delayed earthquake triggering
Sara Beth L Cebry1, Chun-Yu Ke1, Srisharan Shreedharan2,3,4
1School of Civil and Environmental Engineering, Cornell University, Ithaca, NY, 14850, USA.
Nature Communications
|November 11, 2022
Summary
Earthquake sequences arise from complex triggering. Migrating slow slip, acting as on-fault stress meters, reveals fault stress levels and earthquake triggering mechanisms.
Area of Science:
- Geophysics
- Experimental rock mechanics
- Seismology
Background:
- Earthquakes often occur in complex clusters and sequences.
- Delayed triggering of earthquakes is linked to slow subsurface slip, which is difficult to measure directly.
- Understanding fault heterogeneity is key to explaining earthquake complexity.
Purpose of the Study:
- To investigate the origins of earthquake complexity and its relationship to fault heterogeneity.
- To examine the role of slow subsurface slip in delayed earthquake triggering.
- To determine if slow slip phenomena can serve as on-fault stress meters.
Main Methods:
- Utilizing an experimental fault composed of quartz powder and polymer blocks to simulate rock behavior.
- Observing earthquake sequences, including periodic and aperiodic events.
- Measuring local stress and employing numerical simulations.
- Analyzing migrating slow slip phenomena, termed creep fronts.
Main Results:
- Observed a transition from periodic repeating earthquakes to complex sequences of fast and slow events.
- Identified migrating slow slip (creep fronts) facilitating communication between neighboring earthquakes.
- Demonstrated that creep front speed and strength are sensitive to post-earthquake stress levels.
- Validated the potential of creep fronts to function as on-fault stress meters.
Conclusions:
- Experimental fault models can replicate complex earthquake behavior observed in nature.
- Migrating slow slip is a crucial mechanism for earthquake communication and delayed triggering.
- On-fault stress measurements using creep fronts offer new insights into earthquake processes.
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