Dynamic rupture initiation and propagation in a fluid-injection laboratory setup with diagnostics across multiple...

Area of Science:

• Geophysics
• Earthquake Science
• Fluid Dynamics

Background:

• Fluids are known to trigger various slip events, from slow transients to dynamic earthquake ruptures.
• The detailed mechanics and conditions leading to different rupture behaviors are not well understood.

Purpose of the Study:

• To compare earthquake rupture behavior under different fluid injection rates (slow vs. fast).
• To investigate the influence of fluid injection rate on nucleation processes and rupture dynamics.

Main Methods:

• Utilized a laboratory earthquake setup with pressurized fluid injection capabilities.
• Compared rupture behavior under slow (MPa/hour) and fast (MPa/second) fluid injection rates.

Main Results:

• Fast fluid injection triggered dynamic ruptures at lower pressures and smaller scales than predicted, indicating dynamic loading.
• Slow fluid injection led to gradual nucleation and slow slip, consistent with fluid spreading and stress changes.
• Dynamic ruptures over wetted interfaces showed nearly twice the dynamic stress drop compared to dry interfaces.

Conclusions:

• The rate of pore-pressure increase is crucial for understanding nucleation processes in fluid-triggered earthquakes.
• Further research is needed on how friction properties are affected by fluid presence and injection rates.