Active/passive source-based observation experiments and applications of fiber-optic rotational seismometers
CAO Yu-Jia1(), CHEN Yan-Jun2,3(), LI Zheng-Bin2, TENG Yun-Tian1, ZHANG Ding-Fan4
1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2. School of Electronics, Peking University, Beijing 100871, China 3. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, School of Geosciences and Info-Physics, Central South University, Changsha 410083, China 4. Hangzhou Youfu Technology Co., Ltd., Hangzhou 310018, China
In the past two decades, high-sensitivity ring laser gyroscopes have demonstrated the potential of rotational observation data in global seismology. Commercial fiber-optic three-component rotational seismometers have heralded a new development phase of rotational seismography. Field experiments for high-sensitivity portable fiber-optic rotational seismometers in China remain in the initial stage, whereas their relevant data analysis results have been obtained internationally. This study elucidated the co-located observation experiments on six components (6C, including three components of translational motions and three components of rotational motions) of an active source and a natural earthquake, involving experimental schemes, implementation steps, and subsequent data analysis. Moreover, this study revealed the primary factors influencing the experiment results by comparatively analyzing the similarities and differences of experiments. Fiber-optic rotational and conventional seismometers need to be fixed on the same rigid panel to ensure the consistency of received signals. Besides, proper ground coupling and burial processing contribute to high-quality experimental data. The experimental results indicate that water bodies will affect surface wave manifestation and P-wave clarity. These findings, enriching the practical experience in seismic rotational observation experiments, serve as a reference for the design of subsequent rotational observation experiments, thereby assisting in completing the experiments and obtaining higher-quality data. In terms of data application, this study optimized and substantiated the feasibility of the preprocessing scheme, with the backazimuth calculation accuracy improved by 58.8° and 50° at the two active-source measuring points, and by 24.1° and 29.4° at the two passive-source measuring points. The application of six-component seismic data from a single seismic station suggests that additional observation of rotational components can acquire more seismic wavefield information, thus the observation of rotational components can be employed to enhance the utilization of China's massive seismic observation data. Overall, fiber-optic rotational seismometers broaden the boundary of seismic monitoring technology, boost seismology research, and create new possibilities for future earthquake research.
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