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Three-Dimensional Dynamic Rupture Simulations on Partially-Creeping Strike-Slip Faults
  • Julian C. Lozos,
  • David Douglas Oglesby,
  • Gareth Funning
Julian C. Lozos
California State University, Northridge

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David Douglas Oglesby
University of California, Riverside
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Gareth Funning
University of California, Riverside
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Partially creeping faults exhibit complex behavior in terms of which parts of the fault slip seismically versus aseismically. The specific geometry of creeping versus locked fault patches may pose constraints on rupture lengths on partially-creeping faults. We use the 3D finite element method to conduct dynamic rupture simulations on simplified partially-creeping strike-slip faults, to determine whether coseismic rupture can propagate into creeping regions, and how the presence and distribution of creeping regions affects the ability of rupture to propagate across the whole fault. We implement rate-state friction, in which locked zones are represented by rate-weakening behavior and creeping zones are assigned rate-strengthening properties. We model two simplified geometries: a locked patch at the base of a creeping fault and a creeping patch at the surface of a locked fault. In the case of a locked patch within a creeping fault, rupture does not propagate far past the edges of the locked patch, regardless of its radius. The case of a creeping patch within a locked fault is more complicated. The width of the locked areas around the creeping patch determine whether rupture is able to propagate around the creeping patch. Although rupture is always able to propagate at least a small distance into the creeping patch, if the width of the locked zone between the edge of the creeping patch and the end of the fault is too narrow, rupture stops. This simplified parameter study may be useful for understanding first-order behaviors of real-world partially-creeping strike-slip faults.