Source of the great tsunami of 1 April 1946: a landslide in the upper Aleutian forearc
Source of the great tsunami of 1 April 1946: a landslide in the upper Aleutian forearc
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DOI：
10.1016/s0025-3227(03)00305-0
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发表时间：
2004-01-30
期刊：
影响因子：
2.9
通讯作者：
Pratson, LF
中科院分区：
文献类型：
--
作者：
Fryer, GJ;Watts, P;Pratson, LF
1946年4月1日发生的乌尼马克（东阿留申群岛）地震是个谜。这次地震（M-S = 7.1）产生了不成比例的大海啸（M-t = 9.3），造成167人死亡。海啸具有很强的方向性，最大的波浪沿着垂直于阿留申岛弧的一条光束投射。这些海浪刚刚经过夏威夷群岛，穿过太平洋，当他们在南极洲上岸时仍然很大。在近场，海啸有非常高的助跑（苏格兰帽42米），但迅速横向衰减（6米在Sanak村，120公里以东）。没有任何一个震源能够同时解释远场的大波浪窄波束和近场的快速变化。缓慢的破裂，海啸的方向性，在近源波高的快速变化，波的周期，和强大的T相代，一起建议，地震触发的滑坡，而不是一个纯粹的构造源。从美国地质勘探局的格洛丽亚图像中，我们已经确定了1946年余震区内的一个候选滑坡。该滑坡在仅120米深的地方咬入阿留申大陆架，宽25公里，长65公里，体积为200-300公里（3）。具有这些尺寸的滑动将产生与观测相匹配的海啸，同时仍然满足地震数据。这样的边坡破坏似乎是常见的沿着阿留申群岛的前弧，这对海啸预警有严重的影响。(C)2003 Elsevier B. V.保留所有权利。
The Unimak (eastern Aleutians) earthquake of April 1, 1946 is an enigma. The earthquake (M-S = 7.1) produced a disproportionately large tsunami (M-t = 9.3) which killed 167 people. The tsunami was highly directional, and projected its largest waves along a beam perpendicular to the Aleutian arc. Those waves passed just cast of the Hawaiian Islands, ran the length of the Pacific, and were still large when they ran ashore in Antarctica. In the near field, the tsunami had very high runup (42 m at Scotch Cap) but rapid lateral decay (6 m at Sanak Village, 120 km to the east). No earthquake source can simultaneously explain the narrow beam of large waves in the far field and the rapid variation in near-source runup. The slow rupture, the tsunami directivity, the rapid variation in near-source wave heights, the period of the waves, and the strong T-phase generation, together suggest,an earthquake-triggered landslide rather than a purely tectonic source. From USGS GLORIA imagery we have identified a candidate landslide within the aftershock zone of 1946. The slide bites into the Aleutian shelf at a depth of only 120 m, is 25 km across, 65 km long, and has a volume of 200-300 km(3). A slide with these dimensions would produce a tsunami matching the observations while still satisfying the seismic data. Such slope failures appear to be common along the Aleutian forearc, which has serious implications for tsunami warning. (C) 2003 Elsevier B.V. All rights reserved.