ABSTRACT

The distribution of ground motion, displacement, and secondary hazards around active faults is defined by the interaction of tectonic and site characteristics including fault kinematics. As a result of this complexity, recommendations for fault setback distances or avoidance zones are necessarily simplified. We observed distributed vertical coseismic displacement from the 2016 Mw 7.8 Kaikōura earthquake up to c. 500 m on either side of the sinistral-reverse Papatea fault. On average, c. 32% (2.13 m) of vertical displacement was measured at distances >50 m from the Papatea fault. Additionally, in places, there is strong asymmetry where displacement was accommodated over a wider area in the hanging wall of the fault, a common observation around many dip-slip fault ruptures globally. We compare the distribution of displacement around the Papatea fault to the current fault avoidance zone and find that increasing the size of the fault avoidance zone by 10 m captures 11% more area with a high gradient of vertical displacement. Given these results and similar findings for other faults globally, we recommend that existing standards for fault avoidance zones be evaluated to ensure their ongoing efficacy.

摘要

活动断层周围的地震动、位移和次生灾害的分布由构造和场地特征（包括断层运动学）的相互作用来定义。由于这种复杂性，必须简化对断层后退距离或回避区的建议。我们观察到从 2016 年 Mw 7.8 Kaikōura 地震到 c 的分布式垂直同震位移。Papatea 断层左旋逆向两侧各 500 米。平均而言，c。32% (2.13 m) 的垂直位移是在距离 Papatea 断层 > 50 m 的地方测得的。此外，在某些地方，存在强烈的不对称性，位移被容纳在断层上盘的更广阔区域，这是全球许多倾滑断层破裂的常见观察结果。我们将 Papatea 断层周围的位移分布与当前的断层回避区进行比较，发现将断层回避区的大小增加 10 m 可以多捕获 11% 的具有高垂直位移梯度的区域。鉴于这些结果以及全球其他断层的类似发现，我们建议对现有的断层回避区标准进行评估，以确保其持续有效。