Acta Geodaetica et Cartographica Sinica ›› 2022, Vol. 51 ›› Issue (9): 1899-1910.doi: 10.11947/j.AGCS.2022.20210120

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Analysis of seismogenic information of GNSS strain time series based on HHT-EEMD method in Yunnan region

GAO Han1,2, YUAN Xiping1, GAN Shu1, ZHANG Ming3   

  1. 1. College of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China;
    2. Information Center, Yunnan Earthquake Agency, Kunming 650225, China;
    3. Yunnan Quality Checking Center for Surveying and Mapping Products, Kunming 650034, China
  • Received:2021-03-31 Revised:2021-11-22 Published:2022-09-29
  • Supported by:
    Science and Technology Special Project of Yunnan Earthquake Agency(No. 2021ZX02); The National Key Research and Development Program of China(No. 2018YFC1503604)

Abstract: The gestation and occurrence of earthquakes are essentially the inevitable result of the gradual accumulation of stress and strain energy in the crust and their sudden or slow release. Studying the changing process of strain is of great significance to the determination of earthquake risk. Based on the strain time series of GNSS grids in Yunnan region from 2013 to 2019, the Hilbert-Huang transform (HHT) and ensemble empirical mode decomposition (EEMD) analysis method was used to explore the time-frequency characteristics of GNSS strain time series before earthquakes in Yunnan region which was a different method from traditional time-frequency analysis, it was specially suitable for nonlinear and non-stationary signals, and try to mine the seismogenic information carried in the strain time-frequency signal. The paper summarizes the earthquakes corresponding to grids No.23 and No.42 as earthquake examples. The results show that EEMD can decompose signal according to the time characteristic of the data, and can fully retain the characteristics of the data itself in the decomposition process. Its decomposition is objective and adaptive, and can better analyze the change characteristics of seismic signals at different scales. In addition, the Hilbert transform can describe the subtle changes of the signal over time, reflect the instantaneous characteristics of the signal, and has applicability for the abnormal identification. Through the method of EEMD, IMF component anomaly recognition, Hilbert transform method and comprehensive dynamic analysis of strain time series, it can find some potential information on the eve of earthquakes, and provide reference for the determination of dangerous locations of strong earthquakes in Yunnan area in the future.

Key words: GNSS strain time-series, HHT, EEMD, anomaly recognition

CLC Number: