The results of seismic risk assessment of spatially distributed infrastructure systems are significantly influenced by spatial correlation of earthquake intensity measures (IM). The assumption of isotropy is a basis for most of the existing correlation models of earthquake IMs. In this study, the isotropy assumption of intra-event residuals of peak ground velocity (PGV) and peak ground displacement (PGD) is investigated by implementing a nonparametric statistical test. Using recorded IMs of 9 earthquakes, it is concluded that there is not sufficient evidence to support the assumption of isotropy in general, and the set of intra-event residuals of PGV and PGD should be considered as the realization of anisotropic random fields. Investigations show that the anisotropy properties of intra-event residuals of PGV and PGD are related to anisotropy properties of local soil characteristics indicated by average shear wave velocity of soil profile from the 30 m depth to the surface (Vs30). Finally, predictive models are proposed based on obtained results in order to simulate the correlated univariate random fields of PGV and PGD considering anisotropy.

中文翻译：

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研究考虑各向异性的峰值地速和峰值地位移的单变量随机场中的空间相关性

空间分布基础设施系统的地震风险评估结果受地震烈度度量（IM）空间相关性的显着影响。各向同性假设是大多数现有地震 IM 相关模型的基础。在这项研究中，通过实施非参数统计检验来研究峰值地速 (PGV) 和峰值地面位移 (PGD) 的事件内残差的各向同性假设。使用9次地震记录的IMs，得出结论，没有足够的证据支持一般各向同性的假设，PGV和PGD的事件内残差集应视为各向异性随机场的实现。研究表明，PGV和PGD的事件内残差的各向异性特性与局部土壤特征的各向异性特性有关，这些特性由土壤剖面从30 m深度到地表的平均剪切波速度（Vs30）表示。最后，基于获得的结果提出了预测模型，以模拟考虑各向异性的 PGV 和 PGD 的相关单变量随机场。