Acta Geodaetica et Cartographica Sinica ›› 2022, Vol. 51 ›› Issue (1): 63-70.doi: 10.11947/j.AGCS.2022.20210014

• Geodesy and Navigation • Previous Articles     Next Articles

Pre-seismic anomalies and co-seismic gravity changes of 2011 Tohoku-Oki earthquake (Mw 9.0) detected by superconducting gravity data

DONG Jie1, ZHANG Zeyu1, WEN Hanjiang1, SUN Wenke2   

  1. 1. Chinese Academy of Surveying and Mapping, Beijing 100036, China;
    2. College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2021-01-14 Revised:2021-08-17 Published:2022-02-15
  • Supported by:
    The National Natural Science Foundation of China (Nos. 41604067; 41974093; 41331066; 41774088); The Fundamental Research Funds for the Central Universities (Nos. AR2016; AR2103)

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Abstract: High-precision superconducting gravity data had been widely used in the study of geodynamics. The detection of the pre-seismic anomalies and co-seismic gravity changes caused by a huge earthquake is helpful to the study of focal mechanism and early warning. Meanwhile, the co-seismic observations can be used in the inversion of fault slip model. We study the gravity changes caused by the Tohoku-Oki earthquake (Mw 9.0) using the second sampling data in March 2011 of 7 Superconducting Stations in Japan, China and Europe. We obtained the corrected gravity changes by the preprocessing of tide, air-pressure and drift correction, et al. Comparing the 2861 Mb ≥ 4 earthquakes near the Japan island at the same period and analyzing the filtered gravity changes, we can exclude the influence of non-main earthquakes and find the obvious pre-seismic anomalies at frequencies 0.12 Hz ≤ f ≤ 0.18 Hz. The pre-seismic anomalies occurred 89 h before the earthquake for all the stations. The maximum amplitude of pre-seismic anomalies reaches 28×10-8 m/s2 at Medicina. Moreover, the theoretical co-seismic gravity changes simulated by the spherical dislocation theory and the CMT solution, are very close to the observed values of superconducting gravimeters. The absolute values of co-seismic gravity changes are inversely proportional to the epicenter distances.The observations at near-field are closer to the theoretical calculations than that at far-field, and the former can be used as the constraints for fault inversion.

Key words: superconducting gravity data, pre-seismic anomalies, co-seismic gravity changes, Tohoku-Oki earthquake, the spherical dislocation theory

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