Geometric incompatibility in a fault system

Area of Science:

• Geophysics
• Seismology
• Tectonics

Background:

• Fault systems exhibit complex interactions between geometry, movement (kinematics), and seismic activity.
• Understanding stress accumulation and release at fault junctions is crucial for earthquake prediction.

Purpose of the Study:

• To quantify the interdependence between fault geometry, kinematics, and seismicity.
• To introduce and apply measures of geometric incompatibility (G) and kinematic deviation (K) to fault systems.

Main Methods:

• Development of quantitative measures for geometric incompatibility (G) and deviation from kinematic compatibility (K).
• Application of an analog to Stokes formula for regional G and K estimation from boundary data.
• Analysis of G and K changes associated with major seismic events.

Main Results:

• Geometric incompatibility (G) quantifies instability at fault junctions, linked to stress accumulation and seismicity.
• Kinematic deviation (K) reflects unaccounted stress/strain or inconsistencies in fault system reconstruction.
• Estimates for the San Andreas Fault system show recent earthquakes reduced K but had opposing effects on G.

Conclusions:

• Fault junction behavior (locking/unlocking) significantly influences strong earthquake nucleation.
• Geometric incompatibility (G) is a key factor in controlling earthquake initiation processes.
• The study provides tools to integrate diverse fault movement data and assess regional seismic potential.