The subduction zone along the northern Tonga Trench has the highest plate convergence rate in the world, but limited records of its seismic and tsunamigenic activities. In 2009, a tsunami generated by an M_W 8.1 earthquake doublet caused severe impacts in the region including damage and loss of life on the south shores of Upolu and Savaii Islands, Samoa. Here, we use numerical modeling aided by recorded data and eyewitness accounts to evaluate and identify the published source models in the Tonga Trench region that most suitably represent the 2009 event for use in hazard assessment around Samoa. We show that only a few of the published sources are suitable to reproduce the large inundation observed in Samoa, and none reproduces runup as high as observed in the areas that were most severely impacted on the southeast Upolu coast. The distribution and intensity of runup and inundation are dependent on source model, local topographic and bathymetric features, regional coastal geomorphology, and trapping of short‐period waves over the reef flats. The computed results are also influenced by model approximation and grid resolution especially for areas with extreme runup records. Comparison of the relative contributions from the doublet to the southeast Upolu inundation indicates that the initial intraplate normal faulting dominated the east‐northeastward tsunami propagation and inundation compared with the subsequent interplate thrust faulting. Overall, two key source models are discussed and identified for future refinement.

中文翻译：

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源断裂和边缘礁对萨摩亚东南Upolu 2009年南太平洋海啸淹没的影响

汤加海沟北部的俯冲带板块汇聚速度是世界上最高的，但是其地震和海啸发生活动的记录却很少。在2009年，产生由一个海啸中号_W¯¯8.1双重地震在该地区造成了严重影响，包括对萨摩亚乌波卢岛和萨瓦伊群岛南岸的破坏和生命损失。在这里，我们使用数字模型，结合记录的数据和目击者的帐目，来评估和确定汤加海沟地区已发布的源模型，这些模型最适合代表2009年的事件，用于萨摩亚周围的危害评估。我们表明，只有少数已出版的资料适合重现萨摩亚观测到的大面积洪水，没有一个资料能再现如在Upolu东南沿海受到最严重影响的地区所观测到的那样高的洪水。径流和淹没的分布和强度取决于源模型，局部地形和测深特征，区域沿海地貌以及礁滩上短周期波的捕获。计算结果还受到模型逼近和网格分辨率的影响，特别是对于具有超高运行记录的区域。从双重峰到东南部Upolu淹没的相对贡献的比较表明，与随后的板块间逆冲断层相比，最初的板内正断层主宰了东西向海啸的传播和淹没。总体而言，讨论并确定了两个关键源模型以供将来改进。从双重峰到东南部Upolu淹没的相对贡献的比较表明，与随后的板块间逆冲断层相比，最初的板内正断层主宰了东西向海啸的传播和淹没。总体而言，讨论并确定了两个关键源模型以供将来改进。从双重峰到东南部Upolu淹没的相对贡献的比较表明，与随后的板块间逆冲断层相比，最初的板内正断层主宰了东西向海啸的传播和淹没。总体而言，讨论并确定了两个关键源模型以供将来改进。