Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan.
National Research Institute for Earth Science and Disaster Resilience (NIED), Tsukuba, Japan.
Sci Rep. 2021 Feb 2;11(1):2797. doi: 10.1038/s41598-021-82093-8.
A ship-based seismic survey was conducted close to a fiber-optic submarine cable, and 50 km-long distributed acoustic sensing (DAS) recordings with air-gun shots were obtained for the first time. We examine the acquired DAS dataset together with the co-located hydrophones to investigate the detection capability of underwater acoustic (hydroacoustic) signals. Here, we show the hydroacoustic signals identified by the DAS measurement characterizing in frequency-time space. The DAS measurement can be sensitive for hydroacoustic signals in a frequency range from [Formula: see text] to a few tens of Hz which is similar to the hydrophones. The observed phases of hydroacoustic signals are coherent within a few kilometers along the submarine cable, suggesting the DAS is suitable for applying correlation analysis using hydroacoustic signals. Although our study suggests that virtual sensor's self-noise of the present DAS measurement is relatively high compared to the conventional in-situ hydroacoustic sensors above a few Hz, the DAS identifies the ocean microseismic background noise along the entire submarine cable except for some cable sections de-coupled from the seafloor.
在靠近光纤海底电缆的地方进行了基于船舶的地震调查，并首次获得了长达 50 公里的气枪激发分布式声学传感 (DAS) 记录。我们结合共定位的水听器检查所获得的 DAS 数据集，以研究水下声（水声）信号的检测能力。在这里，我们展示了 DAS 测量在频时空间中识别的水声信号特征。DAS 测量对于频率范围为 [Formula: see text] 到几十赫兹的水声信号敏感，与水听器相似。在海底电缆沿线几公里范围内，水声信号的观测相位是相干的，这表明 DAS 适用于使用水声信号进行相关分析。尽管我们的研究表明，与传统的原位水声传感器相比，目前 DAS 测量的虚拟传感器自噪声在几赫兹以上相对较高，但 DAS 除了一些与海底解耦的电缆段外，可识别整个海底电缆沿线的海洋微震背景噪声。
