Sediment grains moved by passing tsunami waves: Tsunami deposits in deep water
- 作者：Robert Weiss
- 关键词：tsunami sediments ; linear wave equation
- 刊名：Marine Geology
- 出版年：2008
- 期刊代码：57_00253227
- 类别：ear
- 出版时间：1 May 2008
- 卷：250
- 期：3-4
- 页码：251-257
- 文件大小：778 K
摘要
Tsunamis propagating in the open ocean have associated horizontal particle velocities that do not change with depth — yet the limiting water depth where a tsunami of given characteristics will initiate sediment motion remains unknown. Based upon linear wave theory and a parametrization of the Shields curve, equations are derived and solved, using an iterative scheme, to address the topic of grain movement by tsunami waves as a function of water depth and wave amplitude. The focus is on waves in deep water where tsunami waves behave linearly and on non-cohesive sediment grains. Furthermore, the question is addressed of which grain sizes are picked up on a sloping beach as the wave shoals. According to the results, even the Boxing Day tsunami in 2004 was incapable of moving fine sand in water deeper than 985 m in the Bay of Bengal and 335 m in the Indian and Pacific oceans. The results suggest that tectonic tsunamis of size equal to or smaller than the Boxing Day tsunami cannot initiate motion of deep-water cohesionless sediments that can be correlated on an oceanic basin-wide scale.