Normal faults are often complex three-dimensional structures comprising multiple sub-parallel segments separated by intact or breached relay zones. Relay zones are classified according to whether they step in the strike or dip direction and whether the relay zone-bounding fault segments are unconnected in 3D or bifurcate from a single surface. Complex fault surface geometry is described in terms of the relative numbers of different types of relay zones to allow comparison of fault geometry between different faults and different geological settings. A large database of fault surfaces compiled primarily from mapping 3D seismic reflection surveys and classified according to this scheme, reveals the diversity of 3D fault geometry. Analysis demonstrates that mapped fault geometries depend on geological controls, primarily the heterogeneity of the faulted sequence and the presence of a pre-existing structure, as well as on resolution limits and biases in fault mapping from seismic data. Where a significant number of relay zones are mapped on a single fault, a wide variety of relay zone geometries occurs, demonstrating that individual faults can comprise segments that are both bifurcating and unconnected in three dimensions.

正断层通常是复杂的三维结构，包括由完整或破坏的中继层隔开的多个次平行部分。根据中继区域是沿走向还是沿下降方向步进，以及中继区域边界断层是未连接3D还是从单个表面分叉，来对中继区域进行分类。根据不同类型的中继带的相对数量来描述复杂的断层表面几何形状，以允许比较不同断层和不同地质设置之间的断层几何形状。大型断层表面数据库主要是通过映射3D地震反射勘测数据汇编而成的，并根据此方案进行分类，从而揭示了3D断层几何的多样性。分析表明，映射断层的几何形状取决于地质控制，主要是断层序列的异质性和既有结构的存在，以及地震数据断层图的分辨率极限和偏差。在单个故障上映射大量继电器区域的情况下，会发生各种各样的继电器区域几何形状，这表明单个故障可以包含在三个维度上都是分叉且未连接的线段。