Estimation of seismic moment and slip distribution of the April 1, 1946, Aleutian tsunami earthquake
Estimation of seismic moment and slip distribution of the April 1, 1946, Aleutian tsunami earthquake
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DOI：
10.1029/97jb00274
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发表时间：
1997-06-10
影响因子：
3.9
通讯作者：
Satake, K
中科院分区：
文献类型：
--
作者：
Johnson, JM;Satake, K
1946年阿留申地震产生了海啸震级M-t=9.3的海啸，但面波震级只有M-s=7.4，属于海啸地震。根据地震数据得出的地震表观规模与海啸规模之间的差异可以用几种机制来解释，包括滑坡和慢震，但几乎没有地震数据可以确定正确的机制。我们利用验潮仪记录的海啸波形来研究海啸的产生机制。我们已经模拟了1946年阿留申海啸的来源，作为一个俯冲地震的结果。我们使用有限差分计算对数据进行了正演和反演建模。计算合成海啸在计算中，我们考虑了由于断层作用引起的海底垂直和水平变形。对海啸波形的反演结果表明，断层上的滑动主要集中在靠近震中的断层浅段。在余震区几乎没有滑动，表明余震可能代表一个余震区或触发地震活动。地震的矩估计为23 × 10（20）N m，或M-w=8.2。大多数波形都可以很好地解释，断层模型和滑动分布，包括檀香山波形，但夏威夷的数据也表明，其他的影响，如滑坡，可能是必要的解释异常海啸振幅在夏威夷。1946年的地震与其他海啸地震类似，如1896年的三陆地震和1992年的尼加拉瓜地震，表明缓慢，浅破裂可能解释了巨大的海啸。
The 1946 Aleutian earthquake produced a tsunami of tsunami magnitude M-t=9.3, but the surface wave magnitude is only M-s=7.4, making it a tsunami earthquake. The discrepancy between the apparent size of the earthquake based on the seismic data and the size of the tsunami has been explained by several mechanisms, including a landslide and a slow earthquake, but there are few seismic data available to determine the correct mechanism. We study the generating mechanism of the tsunami using tsunami waveforms recorded on tide gauges. We have modeled the source of the 1946 Aleutian tsunami as the result of an underthrusting earthquake. We performed both forward and inverse modeling of the data using a finite difference calculation to. compute synthetic tsunamis. We include both vertical and horizontal deformation of the ocean bottom due to faulting in the computation. The results of the inversion of the tsunami waveforms show that the slip on the fault is mainly concentrated in the shallow section of the fault near the epicenter. There is little slip in the area of the aftershocks, indicating that the aftershocks may represent an area of afterslip or triggered seismicity. The moment estimate of the earthquake is 23x10(20) N m, or M-w=8.2. The majority of the waveforms are well-explained by this, fault model and slip distribution, including the Honolulu waveform, but the Hawaiian data also suggest that other effects, such as a landslide, may be necessary for explaining the abnormal tsunami amplitudes in Hawaii. The 1946 earthquake is similar to other tsunami earthquakes, such as the 1896 Sanriku and 1992 Nicaragua earthquakes, indicating that slow, shallow rupture may explain the disproportionally large tsunamis.