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EARTHQUAKE ›› 2021, Vol. 41 ›› Issue (1): 141-152.doi: 10.12196/j.issn.1000-3274.2021.01.011

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Modeling Experiment and Anomaly Analysis of Time-varying Gravity Field in South China

YANG Jin-ling1,2, CHEN Shi1,3, LI Hong-lei1,3, ZHANG Bei1,3, RUAN Ming-ming4   

  1. 1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;
    2. Fujian Earthquake Agency, Fuzhou 350003, China;
    3. Beijing Baijiatuan Earth Science National Observation and Research Station, Beijing 100095, China;
    4. Geophysical Exploration Center, China Earthquake Administration, Zhengzhou 450002, China
  • Received:2020-07-16 Revised:2020-09-18 Online:2021-01-31 Published:2021-01-28

Abstract: The terrestrial time-varying gravity measurement has been used for monitoring the density changes and tectonic movements associated with earthquakes. In order to determine the field source monitoring capability and gravity field characteristics of South China region, a gravity model was constructed based on spherical tesseroid units. To assess the quality of recovered gravity field by different modeling methods, gravity field source modeling experiments and noise tests were carried out. The variation of observed gravitational field was calculated and recovered from 2015 to 2017 using least square collocation method. Overall, it can be concluded that the least squares configuration method performs better gravity field recovering effect and anti-noise ability. The spatial resolution capability of the South China Gravity Survey Network is about 55 km, and the equivalent observable signal is about 30×10-8 m/s2. The accumulative temporal and spatial characteristics of the gravity field between 2015 and 2017 is actually consistent. Negative gravity anomalies continue to increase and accumulate at different time scales, and there are periodic changes in positive and negative fluctuations locally. The results have important value for evaluating the quality of terrestrial gravity data, guiding the transformation and upgrading of gravity observation network, while advancing our standing of the interpretation of gravity field changes, analyzing strong earthquakes and geophysical field changes.

Key words: Time-varying gravity field, Potential field model, Checkerboard tests, Least square collocation, South China region

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