FUNCTIONAL EMULATION OF HIGH RESOLUTION TSUNAMI MODELLING OVER CASCADIA
FUNCTIONAL EMULATION OF HIGH RESOLUTION TSUNAMI MODELLING OVER CASCADIA
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DOI：
10.1214/18-aoas1142
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发表时间：
2018-12-01
影响因子：
1.8
通讯作者：
Dias, Frederic
中科院分区：
文献类型：
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作者：
Guillas, Serge;Sarri, Andria;Dias, Frederic
海啸的罕见性迫使科学界依靠数值模拟进行规划和风险评估，因为从历史事件中获得的实际数据很少。数值模型，也称为模拟器，通常产生时间序列的输出。由于仿真器的计算成本较大，需要统计仿真来完成不确定性量化任务，仿真器可以有效地逼近仿真器。因此，需要创建尊重时间序列输出性质的模拟器。我们在这里介绍了一种新的计算机模型的输入-输出依赖性的统计模拟。我们使用具有两个增强功能的外部产品模拟器。功能配准和功能主成分技术提高了仿真器的预测能力。我们的相位配准方法捕捉振幅的细微变化。对输出时间序列的平滑性进行建模，因此我们能够选择比固定基方法（如傅立叶基）更具代表性和更简洁的回归函数。我们将此方法应用于太平洋西北部卡斯卡迪亚地区的高分辨率海啸波传播和海岸淹没。该分析中的同震表示方法新颖，比以往的研究更加真实。在仿真器的帮助下，我们可以对最大波高对震源特性的敏感性进行分析，并可以将震源特性的不确定性传播到波高，从而对卡斯卡迪亚地区的海啸灾害进行概率性陈述。
The rarity of tsunamis impels the scientific community to rely on numerical simulation for planning and risk assessment purposes because of the low availability of actual data from historic events. Numerical models, also called simulators, typically produce time series of outputs. Due to the large computational cost of such simulators, statistical emulation is required to carry out uncertainty quantification tasks, as emulators efficiently approximate simulators. There is thus a need to create emulators that respect the nature of time series outputs. We introduce here a novel statistical emulation of the input-output dependence of these computer models. We employ the Outer Product Emulator with two enhancements. Functional registration and Functional Principal Components techniques improve the predictions of the emulator. Our phase registration method captures fine variations in amplitude. Smoothness in the time series of outputs is modelled, and we are thus able to select more representative, and more parsimonious, regression functions than a fixed basis method such as a Fourier basis. We apply this approach to the high resolution tsunami wave propagation and coastal inundation for the Cascadia region in the Pacific Northwest. The coseismic representation in this analysis is novel, and more realistic than in previous studies. With the help of the emulator, we can carry out sensitivity analysis of the maximum wave elevation with respect to the source characteristics, and we are able to propagate uncertainties from the source characteristics to wave heights in order to issue probabilistic statements about tsunami hazard for Cascadia.