Duo Li , Alice-Agnes Gabriel 

Transients of aseismic fault slip, slow slip events (SSEs), have been observed in spatial and temporal
proximity to the initiation of megathrust earthquakes. However, the underlying physics potentially connecting a preceding SSE to earthquake rupture remains to be determined. Here, we link 3D
observation-driven slow-slip cycle models with dynamic rupture simulations of the 2014 Mw7.3 Guerrero, Mexico earthquake across the geometrically complex flat-slab Cocos plate. Our physics-based models reproduce key regional geodetic and teleseismic observations on timescales ranging from decades to
seconds. We find that accelerating SSE fronts transiently increase shear stress at the down-dip end of the seismogenic portion of the megathrust. The stresses cast by the 2014 Mw 7.6 SSE are significantly
larger than those during the three previous episodic SSEs, and can dynamically initiate earthquake
rupture. We show that in addition to the transient stresses caused by SSEs, megathrust asperities
explain the observed complexities in the coseismic energy release and static surface displacements. We
conclude that it is crucial to jointly analyze the long- and short-term interactions of SSEs and megathrust
earthquakes across several (a)seismic cycles. Our study has important implications for identifying
earthquake precursors and understanding megathrust faulting processes.