Foreshock and aftershocks in simple earthquake models.

Area of Science:

• Geophysics
• Computational Seismology
• Complex Systems

Background:

• Earthquake fault models often link Gutenberg-Richter scaling to triggering processes.
• Natural fault systems exhibit diverse behaviors due to heterogeneous geometries and physical properties.
• Understanding the interplay between triggering and fault structure is crucial for explaining observed seismic phenomena.

Purpose of the Study:

• To investigate how spatial heterogeneities, specifically stronger asperity cells, influence earthquake triggering and fault system behavior.
• To develop a cellular automata model that incorporates these heterogeneities and reproduces natural seismicity patterns.
• To explore the relationship between fault structure, triggering processes, and observed seismic phenomena like Gutenberg-Richter scaling and foreshock-aftershock sequences.

Main Methods:

• Utilized a cellular automata model based on Olami-Feder-Christensen and Rundle-Jackson-Brown models.
• Incorporated long-range interactions and a fixed percentage of stronger asperity cells into the lattice.
• Simulated stress accumulation and rupture dynamics within the heterogeneous fault model.

Main Results:

• The introduction of asperity cells led to temporal clustering of earthquakes, mimicking natural fault systems.
• The model reproduced Gutenberg-Richter scaling, a fundamental observation in seismology.
• Observed sequences of foreshocks, a main shock, and aftershocks, consistent with natural earthquake patterns.
• Demonstrated that spatial heterogeneity significantly influences seismic patterns, beyond simple cascade mechanisms.

Conclusions:

• Spatial heterogeneity, represented by stronger asperity cells, is a key factor in generating realistic earthquake temporal clustering and scaling laws.
• The developed model provides further evidence that observed spatial and temporal patterns in seismicity are strongly influenced by the underlying physical properties of fault systems.
• This research highlights the importance of incorporating structural complexities into earthquake models to accurately represent natural seismic behavior.