Seismic Detection of Oceanic Internal Gravity Waves from Terrestrial Observations
Seismic Detection of Oceanic Internal Gravity Waves from Terrestrial Observations
复制标题
通过地面观测对海洋内重力波进行地震探测
DOI：
10.1002/essoar.10507103.1
复制
发表时间：
2021
期刊：
影响因子：
8.4
通讯作者：
Davis, Kristen A.
中科院分区：
文献类型：
--
作者：
Shaddox, Heather R.;Brodsky, Emily E.;Ramp, Steven R.;Davis, Kristen A.
海洋重力内波在水柱中沿着密度分层传播，并且是普遍存在的。它们可以传播数千公里，然后打破浅滩水深测量，随之而来的湍流混合影响海岸过程和气候反馈。尽管它们的重要性，内波本质上是难以检测的，因为它们只会导致海面的微小幅度偏转;需要全球检测和长时间序列的内波激发了地球物理检测方法的搜索。传播的内波与倾斜海底的压力耦合提供了产生地震可观测信号的潜在机制。我们使用的数据，从南中国海，特殊的海洋和卫星时间序列可用于比较，以确定第一次在陆上被动地震数据集的内波信号。我们在2019年5月至6月东沙环礁附近的海洋和卫星数据的背景下分析了宽带地震仪上的潜在地震信号，并发现瞬态地震倾斜信号与海洋和卫星数据中的内波到达和碰撞之间存在有希望的相关性。看来，我们已经成功地检测到海洋内波使用陆上地震仪。这一初步探测表明，陆上地震探测和海洋内波的振幅测定是可能的，并可能用于扩大历史记录，利用现有的岛屿和沿海地震台站。
Oceanic internal gravity waves propagate along density stratification within the water column and are ubiquitous. They can propagate thousands of kilometers before breaking in shoaling bathymetry and the ensuing turbulent mixing affects coastal processes and climate feedbacks. Despite their importance, internal waves are intrinsically difficult to detect as they result in only minor amplitude deflection of the sea surface; the need for global detection and long time series of internal waves motivates a search for geophysical detection methods. The pressure coupling of a propagating internal wave with the sloping seafloor provides a potential mechanism to generate seismically observable signals. We use data from the South China Sea where exceptional oceanographic and satellite time series are available for comparison to identify internal wave signals in an onshore passive seismic data set for the first time. We analyze potential seismic signals on broadband seismometers in the context of corroborating oceanographic and satellite data available near Dongsha Atoll in May–June 2019 and find a promising correlation between transient seismic tilt signals and internal wave arrivals and collisions in oceanic and satellite data. It appears that we have successfully detected oceanic internal waves using a subaerial seismometer. This initial detection suggests that the onshore seismic detection and amplitude determination of oceanic internal waves is possible and can potentially be used to expand the historical record by capitalizing on existing island and coastal seismic stations.