Arcuate stress state in accretionary prisms from real-scale numerical sandbox experiments

Area of Science:

• Geophysics
• Tectonics
• Computational modeling

Background:

• Accretionary prisms play a crucial role in seismic energy accumulation and release.
• Understanding stress states within these prisms is vital for seismic hazard assessment.
• Traditional sandbox experiments face limitations in directly measuring stress states.

Purpose of the Study:

• To investigate the 3D stress state within accretionary prisms using numerical simulations.
• To identify the mechanisms responsible for fault undulations observed in accretionary prisms.
• To correlate in-situ stress orientation with regional and local stress regimes.

Main Methods:

• Real-scale numerical sandbox experiments were conducted.
• The discrete element method (DEM) was employed for simulations.
• Analysis focused on stress orientation changes and fault morphology.

Main Results:

• Macro-scale fault undulations, mimicking natural structures, emerged despite uniform initial conditions.
• Stress arches were identified as the cause of these undulations.
• The formation of stress arches is linked to discontinuous stress orientation changes during stress chain rearrangement.

Conclusions:

• The study elucidates the role of stress arches in accretionary prism deformation.
• In-situ stress orientation can indicate regional plate convergence or local stress arch effects.
• Findings can improve long-term seismic monitoring strategies, particularly in tectonically active zones like the Nankai Trough.