Research On The Processing Method And Application Of Superconducting Gravity Observation Data

Processing and analyzing continuous gravity observations on the Earth’s surface and studying the gravitational tidal signals contained in them are indispensable prerequisites for studying geodynamic processes and explaining geophysical phenomena.The mass redistribution and changes in the Earth’s interior caused by earthquakes also provide researchers with a wealth of valuable information.The research object of this paper is the continuous observation data of the superconducting gravimeter(OSG-066)at Lijiang Earthquake Center Station from January 2020 to June 2021.The tidal parameters are obtained by tide analysis software,the ocean tide model is studied based on the calculation method of ocean tidal load effect,and the coseismic gravity variations of the Yangbi MS 6.4 earthquake and the Maduo MS 7.4 earthquake are obtained by using the quadratic function method and the spherical earth seismic dislocation theory.The OSG superconducting gravimeter at the Lijiang Earthquake Center Station has been continuously observed for nearly 10 years,providing a number of valuable observation data for studying the properties of underground media in the surrounding area.In order to obtain the accurate gravity tide parameters in Lijiang area,this paper uses Baytap-G and Eterna to analyze respectively the data of the superconducting gravity observation at the Lijiang Earthquake Center Station from January 2020 to June 2021,and compare the tide analysis results of them.The results show that Eterna can obtain more accurate and comprehensive gravity tide parameters when processing long-term continuous gravity observation data.We use 2 days’ continuous observation data recorded with the GWR OSG superconducting gravimeter before and after the 2021 Yangbi MS 6.4 earthquake and Maduo MS 7.4 earthquake,to extract the gravity residual time series and the signal of coseismic gravity changes through harmonic analysis.The observed coseismic gravity changes of the Yangbi MS 6.4 earthquake and the Maduo MS 7.4 earthquake are about-4.37 nm·s-2 and 28.57 nm·s-2,respectively.At the same time,the coseismic gravity changes caused by the above two earthquakes at Lijiang Earthquake Center Station are calculated by using the spherical dislocation theory.The theoretical coseismic gravity changes are about 1-2 order smaller than the observed results as a whole.Specifically,the theoretical values are about-0.19 nm·s-2 of the Yangbi MS 6.4 earthquake)and 0.24 nm·s-2 of the Maduo MS 7.4 earthquake,which are the same magnitude as the gravitational changes caused by groundwater.This indicated that the superconducting gravimeter was affected by the "pulse signal" of the earthquakes.The observations show a significant increased drift in gravity signals during the two great earthquakes.