海陆联合大跨度多点位海底大地电磁同步数据采集

海底电磁探测是研究海洋基础地学课题和海底矿产资源分布的重要地球物理方法之一。由于大地电磁场存在区域噪声,因而,为压制干扰并获得高质量的场源数据,就需进行带远参考方式的数据采集。在采集过程中,包括陆上基站和海底测网的多台仪器应遵循同一个时间基准和统一的方位坐标。海底大地电磁仪为满足上述要求,其内部配备了高精度时钟源、姿态检测器件以及与海底电磁信息采集相关的自动信号测量与存储电路。海上作业时,科考船沿预定航线,实现仪器的逐点投放。海底测量结束后,通过遥控方式改变海底仪器的浮力性质,使其自动返回海面。近期的海洋试验表明,中国的海底大地电磁探测技术已实现了实用化,可为海洋勘查提供高技术支撑。

Long-span and Multi-point Synchronizing Data Acquisition for Seafloor Magnetotelluric Based on Union of Marine and Land

Electromagnetic prospecting on the seafloor is one of the important geophysical methods to research the marine geology topics and the seafloor mineral resources. The data acquisition of remote reference is used to suppress interference and acquire the high quality data due to the magnetotelluric regional noise. The base station on land and surveying net under the water should follow simultaneous observation and the same location coordinates in the acquisition process. In order to solve the problems above, the high-precision clock, detecting posture device and automatic measurement circuit are equipped in marine magnetotelluric instrument. The instruments are placed point-to-point when the ship carries out marine experiments along scheduled routes. The characteristic of instrument flotage changes by remote control to let it automatic return to offing after the acquisition completes. Recent marine experiments indicate that the seafloor magnetotelluric prospecting in China have achieved utility and can offer high technology support in marine prospecting.