Coseismic surface faulting is a significant source of hazard for critical plants and distributive infrastructure; it may occur either on the principal fault or as distributed rupture on nearby faults. Hazard assessment for distributed faulting is based on empirical relations which, in the case of normal faults, were derived almost 15 years ago using a dataset of US earthquakes. We collected additional case histories worldwide, for a total of 21 earthquakes, and calculated the conditional probability of distributed faulting as a function of distance from the principal fault. We found no clear dependency on the magnitude nor the time of occurrence of the earthquakes, but our data consistently show a higher probability of rupture when compared with the scaling relations currently adopted in engineering practice. We derive updated empirical regressions and show that the results are strongly conditioned by the averaging of earthquakes effectively generating distributed faulting at a given distance and those which did not generate faulting; thus, we introduce a more conservative scenario that can be included in a logic tree approach to consider the full spectrum of potential ruptures. Our results can be applied in the framework of probabilistic assessment of fault displacement hazard.

中文翻译：

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正断层地震中分布地表破裂的条件概率

同震地表断层是关键工厂和分布式基础设施的重要危险源；它可能发生在主断层上，也可能发生在附近断层上的分布式破裂。分布式断层的危害评估基于经验关系，就正断层而言，该关系是在大约 15 年前使用美国地震数据集得出的。我们收集了世界范围内总共 21 次地震的其他案例历史，并计算了分布断层的条件概率作为与主断层距离的函数。我们发现没有明显依赖于地震的震级和发生时间，但与目前工程实践中采用的比例关系相比，我们的数据始终显示出更高的破裂概率。我们推导出更新的经验回归，并表明结果受地震的平均影响，在给定距离有效地产生分布断层和没有产生断层的地震；因此，我们引入了一个更保守的场景，可以包含在逻辑树方法中，以考虑所有潜在的破裂。我们的结果可以应用于断层位移危险的概率评估框架。