Is ambient noise tomography across ocean basins possible?
Is ambient noise tomography across ocean basins possible?
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DOI：
10.1029/2006gl026610
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发表时间：
2006-07
影响因子：
5.2
通讯作者：
F. Lin;M. Ritzwoller;N. Shapiro
中科院分区：
文献类型：
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作者：
F. Lin;M. Ritzwoller;N. Shapiro
基于在太平洋盆地内或邻近的66个台站获得的宽带地震记录的长达一年的互相关，我们发现宽带环境噪声在岛屿台站之间以及岛屿台站和大陆台站之间相干传播。对于许多站对，观察到高信噪比（SNR）的基模瑞利波绿色函数，这为跨太平洋的环境噪声层析成像奠定了物理基础。在陆地和海洋台站的环境噪声水平与“噪声相干距离”（观测到台站高信噪比互相关信号的最长距离）之间的关系中，也观察到了类似的趋势。由于本地产生的噪声掩盖了长距离的相干噪声，位于安静的岛屿上的位置站是必要的环境噪声层析成像的成功。在环礁地点，以及根据对H2O观测站数据的分析，在海底地点，周期超过1025秒时，当地噪音构成了特别的挑战。
Based on year‐long cross‐correlations of broad‐band seismic records obtained at sixty‐six stations within or adjacent to the Pacific Basin, we show that broad‐band ambient noise is observed to propagate coherently between island stations and between island and continent stations. For many station pairs, high signal‐to‐noise ratio (SNR) fundamental mode Rayleigh wave Green functions are observed, which establishes the physical basis for ambient noise tomography across the Pacific. Similar trends for continental and oceanic stations are observed in the relationship between the ambient noise level at a station and the “noise coherence distance” – the longest distance at which a high SNR cross‐correlation signal is observed for a station. Because locally generated noise obscures long distance coherent noise, situating stations at quiet locations on islands is necessary for the success of ambient noise tomography. Local noise poses a particular challenge at atoll sites and, on the basis of analysis of data from station H2O, at ocean bottom sites at periods above ∼25 sec.