Sensitivity of Tsunami Data to the Up-Dip Extent of the July 2021 Mw 8.2 Alaska Earthquake
Sensitivity of Tsunami Data to the Up-Dip Extent of the July 2021 Mw 8.2 Alaska Earthquake
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DOI：
10.1785/0220210359
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发表时间：
2022-05
影响因子：
3.3
通讯作者：
I. Mulia;A. Gusman;M. Heidarzadeh;K. Satake
中科院分区：
文献类型：
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作者：
I. Mulia;A. Gusman;M. Heidarzadeh;K. Satake
2021年7月，阿拉斯加-阿留申俯冲带发生了一次规模为Mw 8. 2的大海啸地震。为了揭示事件的特点，我们首先应用频谱和小波分析，在本地和太平洋范围内的海平面观测网络记录的诱发海啸。由于地震相对较深（30公里），因此在公海和沿海地区产生的最大海啸振幅分别仅为2.5厘米和2.50厘米。然而，由于该地区独特的地质特征，海啸的主要周期为57-73分钟，比类似规模的巨型逆冲地震通常产生的时间要长。此外，我们比较了从各种数据集推断的多个源模型，并评估了它们在重建观测到的海啸波形方面的性能。比较结果表明，破裂区的上倾极限必须限制在1020公里的深度，以准确地再现所观察到的海啸波形。较浅的滑动超过规定的限制导致高估的海啸振幅。这意味着地震不太可能破坏海沟附近的板块界面。
A large tsunamigenic earthquake of magnitude Mw 8.2 occurred on the Alaska-Aleutian subduction zone in July 2021. To reveal the characteristics of the event, we first applied spectral and wavelet analyses to the induced tsunami recorded both at the local and Pacific-wide sea level observation networks. Because the earthquake was relatively deep (∼30 km), the resultant maximum tsunami amplitudes were only ∼5 and ∼50 cm in the open ocean and coastal area respectively. However, owing to the unique geological feature of the region, the tsunami had dominant periods of 57–73 min, which are longer than that typically generated by similar-size megathrust earthquakes. Furthermore, we compared multiple source models inferred from various data sets and evaluated their performances in reconstructing the observed tsunami waveforms. The comparison results suggest that the up-dip limit of the rupture area must be restricted at depth of ∼20 km to accurately reproduce the observed tsunami waveforms. Shallower slips beyond the prescribed limit led to an overestimation of the tsunami amplitude. This implies that the earthquake was unlikely to rupture the plate interface on the near trench section.