Aftershocks are fluid-driven and decay rates controlled by permeability dynamics.

Area of Science:

• Earthquake physics
• Seismology
• Geophysics

Background:

• The variability in earthquake aftershock generation and decay rates remains poorly understood.
• Existing empirical models, like the Omori-Utsu Law, do not fully explain these observations.

Purpose of the Study:

• To investigate the link between earthquake aftershock productivity and decay rates.
• To explore the role of high-pressure fluid sources in driving aftershock sequences.
• To develop a physical model explaining aftershock phenomena.

Main Methods:

• Development of a physical model for crustal permeability dynamics.
• Comparison of model predictions with observational data.
• Analysis of the relationship between aftershock decay and tectonic healing of fracture networks.

Main Results:

• A dearth of aftershocks correlates with the absence of deep high-pressure fluid sources.
• Abundant and long-lasting aftershock sequences are linked to tapping high-pressure fluid reservoirs.
• The proposed physical model provides superior fits to observations compared to the Omori-Utsu Law.

Conclusions:

• Aftershock behavior is fundamentally controlled by the presence and dynamics of crustal fluids.
• The model offers insights into seismic velocity recovery, attenuation, and migration phenomena.
• This work advances the understanding of earthquake aftershock physics and its implications.