The Dynamics of Unlikely Slip: 3D Modeling of Low‐Angle Normal Fault Rupture at the Mai'iu Fault, Papua New Guinea

Despite decades-long debate over the mechanics of low-angle normal faults (LANFs) dipping less than 30°, many questions about their strength, stress, and slip remain unresolved. Recent geologic geophysical observations have confirmed that gently detachment can at such shallow dips host moderate-to-large earthquakes. Here, we analyze first 3D dynamic rupture models to assess how different stress strength conditions affect characteristics LANF We model observationally constrained spontaneous under loading on active Mai'iu fault in Papua New Guinea, which 16°–24° surface accommodates ∼8 mm/yr horizontal extension. four distinct fault-local scenarios: (1) Andersonian extension, as inferred hanging wall; (2) back-rotated principal stresses paleopiezometrically from exhumed footwall; (3) favorably rotated well-aligned for normal-sense slip; (4) extension derived depth-variable static friction decreasing toward surface. Our modeling suggests subcritically stressed moderate earthquakes within purely fields. Near-surface is impeded by free-surface interactions effects geometry frictionally stable gouges shallowest portion fault. Although inclined been proposed some detachments, these are not necessary seismic faults. results demonstrate integrated constrain parameters develop realistic scenarios may pose significant tsunami hazards nearby communities.