Coseismic changes in slip direction recorded by curved slickenlines on fault surfaces are commonly observed following surface-breaking earthquakes. Such observations represent a dynamic record of seismic slip and may provide a new set of constraints on the evolution of propagating rupture and hence earthquake dynamics. We test this hypothesis by conducting dynamic rupture simulations of the 2011 M_w 6.6 Fukushima-Hamadori Earthquake (Japan). These simulations aim to reproduce the well-documented field observations of curved slickenlines that formed during coseismic fault displacement at the ground surface. We consider relatively simple dynamic rupture models with a dipping fault embedded into a homogeneous or layered elastic halfspace. Among a wide range of model parameters tested, we find a model with shallow (<1.5 km) low-velocity layers derived from a regional 3D velocity model combined with a depth-dependent prestress result in curved slip trajectories that closely match slickenline observations. This same model also generates a slip distribution and rupture propagation direction consistent with published inversions constrained by seismological and geodetic data. Furthermore, the characteristics of slickenline curvature are consistent with theoretically predicted earthquake rupture direction. Unlike previous theoretical studies, coseismic changes in rake angle occur due to the emergence of multiple slip fronts within the shallow low-velocity medium. Our results indicate that on-fault geological observations can supplement seismological studies of earthquake rupture evolution beyond traditional datasets.

通常在断层地震之后观察到断层表面上弯曲的斯克莱肯线记录的滑动方向的同震变化。这样的观测结果代表了地震滑动的动态记录，并且可能对传播破裂的发展以及地震动力学提供了新的约束条件。我们通过对2011 M _w进行动态破裂模拟来检验该假设6.6福岛-羽岛地震（日本）。这些模拟旨在重现在地面上同震断层位移过程中形成的弧形滑线的现场记录观测资料。我们考虑相对简单的动态破裂模型，其中将倾覆断层嵌入到均匀或分层的弹性半空间中。在测试的各种模型参数中，我们发现一个浅（<1.5 由区域3D速度模型和与深度相关的预应力相结合得出的km）低速层导致弯曲滑移轨迹与滑移线观测值非常匹配。该模型还产生了与地震和大地测量数据所约束的已公布反演相一致的滑动分布和破裂传播方向。此外，钢丝弯曲曲率的特征与理论上预测的地震破裂方向是一致的。与以前的理论研究不同，前倾角的同震变化是由于浅层低速介质中出现了多个滑动前缘而引起的。我们的结果表明，断层地质观测可以补充传统数据集以外的地震破裂演化的地震学研究。