Geomagnetic Field Change before and after Maduo MW7.3 Earthquake Based on Repeat Geomagnetic Measurement Data
In this paper,repeat geomagnetic measurement data in the surrounding areas of Maduo MW7.3 earthquake from 2016 to 2021 are collected.Then,the Taylor polynomial spatial reference field method is used to correct the diurnal variation of geomagnetic,while the natural orthogonal componentmethod is used to correctthe secularvariation of the geomagnetic field.In this way,the characteristics of geomagnetic field before and after Maduo MW7.3 earthquake are obtained.Further,errors in the results are obtained through analyzing the measurement and the data processing,and on the basis of it,the geomagnetic field changes are corrected.The results indicate that the annual variation of the lithospheric magnetic field in 1～2 years before the Maduo MW7.3 earthquake shows an obvious trend turn,and the change amount is 5～10 nT.The seismic cycle analysis according to the velocity-state-dependent friction law shows that the amount of fault slip before the earthquake is small,and so the annual variation of the lithosphere geomagnetic field is not caused by the stress disturbance related to the pre-seismic fault slip.The electromagnetic effect related to the changes in underground fluid before the Maduo MW7.3 earthquake is more likely to be responsible for changes of the lithosphere geomagnetic field.
Maduo MW7.3 earthquakerepeat geomagnetic measurementlithosphere geomagnetic field changestressfriction law
万方数据
