Fukushima Shun, Shinohara Masanao, Yamada Tomoaki, Hino Ryota, Azuma Ryosuke, Ito Yoshihiro, Yamashita Yusuke, Takano Hiroki
Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Sendai, Japan.
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan.
Sci Rep. 2025 May 24;15(1):18111. doi: 10.1038/s41598-025-01190-0.
P-wave velocity (Vp) structures in marine areas have been estimated using marine airgun-source seismic surveys and refraction methods. The lateral resolution of Vp structures depends on the number of receivers and shots. In marine environments, Vp resolution is often limited due to the sparse distribution of ocean bottom seismometers (OBSs). Recently, distributed acoustic sensing (DAS) offers a cost-effective alternative, providing high-density strain measurements along optical fiber cables. This study demonstrates that seismic refraction using DAS data is effective for imaging shallow Vp structures with high lateral resolution. A seismic survey was conducted using R/V Hakuho-maru, airgun sources, and DAS and OBS measurements along a seafloor optical fiber cable off Sanriku, Japan. Strong lateral heterogeneities in the Vp structure were observed, due to the dense spatial sampling of DAS data. The two-dimensional Vp structure obtained from the DAS data showed good agreement with the seismic reflection profile. This experiment highlights the unique advantages of DAS data over OBSs for seismic refraction.
利用海洋气枪震源地震勘探和折射方法估算了海洋区域的纵波速度（Vp）结构。Vp结构的横向分辨率取决于接收点和炮点的数量。在海洋环境中，由于海底地震仪（OBS）分布稀疏，Vp分辨率常常受到限制。最近，分布式声学传感（DAS）提供了一种经济高效的替代方案，可沿光纤电缆提供高密度应变测量。本研究表明，利用DAS数据进行地震折射对于高横向分辨率成像浅层Vp结构是有效的。利用“白胡丸”号科考船、气枪震源以及沿日本三陆附近海底光纤电缆进行的DAS和OBS测量开展了一次地震勘探。由于DAS数据的密集空间采样，观测到Vp结构中存在强烈的横向非均质性。从DAS数据获得的二维Vp结构与地震反射剖面显示出良好的一致性。该实验突出了DAS数据在地震折射方面相对于OBS的独特优势。
