Evidence for a difference in rupture initiation between small and large earthquakes

Area of Science:

• Seismology
• Earthquake rupture dynamics
• Fault zone mechanics

Background:

• Earthquake rupture nucleation and propagation are studied via lab experiments and theory, but real-world fault zone observations are scarce.
• Predicting earthquake magnitude during rupture remains an open scientific challenge.
• Existing models for earthquake rupture are diverse, highlighting the need for observational constraints.

Purpose of the Study:

• To investigate if P-wave peak displacement evolution can predict earthquake size in real-time.
• To establish a proxy for final rupture size based on early-stage seismic wave characteristics.
• To explore the relationship between fault properties and earthquake growth potential.

Main Methods:

• Analysis of P-wave peak displacement evolution over time for a set of analyzed earthquakes.
• Comparison of displacement growth patterns between small and large seismic events.
• Correlation of earthquake rupture behavior with critical slip distance and slip-weakening distance.

Main Results:

• The evolution of P-wave peak displacement serves as an informative early indicator of rupture process.
• Small earthquakes exhibit rapid initial peak displacement increase, while large earthquakes show slower growth.
• Earthquakes in regions with larger critical slip distances are more likely to develop into large ruptures.

Conclusions:

• P-wave peak displacement can be utilized as a proxy to forecast the final magnitude of an earthquake during its early stages.
• The rate of P-wave peak displacement growth is inversely related to the final earthquake magnitude.
• Fault properties, specifically critical slip distance, significantly influence the potential for an earthquake to become large.