How earthquake ruptures evolve and propagate are major outstanding questions in seismology. Our current understanding is limited to modern events captured by seismic networks, making it impossible to observe rupture propagation that occurred during earthquakes in the distant past. Here we propose a new method to discern the rupture propagation directions of past large earthquakes based on geological features preserved on fault slip planes. These features—called slickenlines—are striations formed during seismic slip and record dynamic fault movement during past surface‐breaking earthquakes. We develop a theoretical framework that links slickenline curvature with rupture mode and rupture propagation direction for all faulting types and test our model using a global catalogue of historical surface‐rupturing earthquakes with seismologically constrained rupture directions. Our results reveal that historical observations are consistent with theoretical predictions, thus providing a robust way to uncover the rupture directions of large earthquakes that lack instrumental data.

中文翻译：

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地震破裂方向的断层地质指纹

地震破裂如何发展和传播是地震学中的主要悬而未决的问题。我们目前的理解仅限于地震网络捕获的现代事件，因此无法观察到遥远过去的地震期间发生的破裂传播。在这里，我们提出了一种基于断层滑动面上保留的地质特征来识别过去大地震破裂传播方向的新方法。这些特征称为滑动线（slickenlines），是在地震滑动过程中形成的条纹，并记录了过去断层地震中的动态断层运动。我们建立了一种理论框架，将所有断裂类型的断裂线与断裂模式和断裂传播方向联系起来，并使用具有地震学约束的断裂方向的历史地表地震的全球目录来测试我们的模型。我们的结果表明，历史观测与理论预测相符，从而为发现缺乏仪器数据的大地震的破裂方向提供了一种可靠的方法。