2010年12月—2011年3月在南海西南次海盆开展了海底地震仪(Ocean Bottom Seismometer, OBS)探测, 采用Sedis IV型、I-4C型和MicrOBS3种不同型号的OBS, 以4×24.5L的大容量气枪为震源, 获得了覆盖西南次海盆残留扩张脊的3D人工地震数据。从处理的地震数据可知, 此次试验是一次比较成功的地震实验, OBS地震记录清晰、震相丰富, 所使用的气枪有足够的能量输出, 显示了其良好的工作能力。选取剖面1中的7台OBS进行了2D剖面处理。初步建模结果表明, 南海西南次海盆地壳结构为普通洋壳, 海山顶部沉积层很薄, 莫霍面埋深较浅。
During December 2010 and March 2011, Ocean Bottom Seismometer (OBS) experiment was carried out in the southwest sub-basin of the South China Sea (SWSB). Three types of OBS, Sedis IV type, I-4C type and MicrOBS type, were used in the experiment, and the energy source was supplied by 4?24.5L large volume air-gun. High quality seismic data that covered the extinct mid ocean ridge of the SWSB were acquired. The data could provide evidence for oceanic crust structure of the SWSB and seafloor spreading course, among others. The data of the seven stations of Profile 1 have been processed, which shows that the seismic records are clear and seismic phases are abundance and that the air-guns had enough energy supplies. Seismic phase analysis and first arrival tomography indicate that the crust of the SWSB is normal oceanic crust with a thin sedimentary layer on the seamount and shallow moho, which provides a good foundation for future research.
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