Quasi-dynamic simulations demonstrate that 3D fault geometry generates slow and fast earthquakes in segmented faults, indicating structural complexity alone dictates rupture styles.
Key Points
To determine how 3D fault geometry and segment interactions govern the emergence of slow slip events and fast earthquakes under uniform friction conditions.
Conducted 3D quasi-dynamic numerical simulations of two parallel faults governed by uniform rate-weakening friction, accelerated with hierarchical matrix algorithms.
Quantified interaction strength across fault configurations using the maximum Coulomb stress induced by a unit stress drop on an adjacent fault.
Identified four distinct slip regimes arising purely from geometric interaction: periodic earthquakes, coexisting slow slip events (SSEs) and earthquakes, isolated SSEs, and complex sequences, whereas single planar faults produced only earthquakes.
Observed that SSEs occur exclusively at intermediate interaction strengths, while low interaction generates periodic earthquakes and high interaction produces irregular, variable-magnitude sequences.
Demonstrated that evolving traction heterogeneity from geometric complexity reproduces empirical moment–duration scaling and reveals sensitivity to detection thresholds.