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Abstract Fault regions inferred to be slowly slipping are interpreted to accommodate much of tectonic plate motion aseismically and potentially serve as barriers to earthquake rupture. Here, we build on prior work using simulations of earthquake sequences with enhanced dynamic fault weakening to show how fault regions that exhibit decades of steady creep or transient slow‐slip events can be driven to dynamically fail by incoming earthquake ruptures. Following substantial earthquake slip, such regions can be under‐stressed and locked for centuries prior to slowly slipping again. Our simulations illustrate that slow fault slip indicates that a region is sufficiently loaded to be failing about its quasi‐static strength. Hence, if a fault region is susceptible to failing dynamically, then observations of slow slip could serve as an indication that the region is critically stressed and ready to fail in a future earthquake, posing a qualitatively different interpretation of slow slip for seismic hazard. 

Geometric moment is accumulated and released throughout the earthquake cycle and can be imaged over both co- and inter-seismic time intervals with geodetic data. Recent dynamic earthquake cycle models have shown that substantial coseismic slip may occur in regions that exhibit low levels of moment accumulation during decadal-scale pre-earthquake epochs. We estimate that <1% of the region that slipped coseismically during the 2024 MW = 7.1 Hyuganada Sea (offshore southeastern Japan) earthquake was co-located with a region of pre-event moment accumulation. This stands in contrast with the behavior of the 2011 MW = 9.1 Tohoku-Oki(offshore northeastern Japan) earthquake, where ∼98% of the coseismic rupture area was co-located with pre-seismic moment accumulation. This co-location of coseismic slip and pre-seismic moment release proximal to the 2024 Hyuganada Sea earthquake serves as a real-world observation consistent with a novel theoretical prediction and is consistent with a perspective that decadal-scale pre-earthquake coupling estimates may provide snapshots of a highly time-variable fault system behavior, and may not necessarily serve as diagnostic identifiers of regions facing short-term earthquake hazard.