Abstract
The correction of the secular variation (SV) of the main geomagnetic field is a key link of field seismogeomagnetic data processing, and the current method relies on the observatory data for the relevant technical processing. To optimize the data products and obtain more accurate and reliable seismomagnetic information, this study adopted a new technical idea, which uses the repeated survey data from field stations to obtain the SV of the main geomagnetic field over the survey area by the weighted least-squares method, and compared the results with those of the current methods. The results were as follows: 1. The SV results of the main geomagnetic field produced by the new method are closer to those of the International Geomagnetic Reference Field (IGRF)_SV model. The mean square error (MSE) of the difference of the three elements F, D, and I between the new method and the IGRF_SV model is 10.7%, 47.0%, and 14.5% of that of the original method, respectively. 2. By applying the new SV correction method, more stable and reasonable variations in Earth’s crustal magnetic field can be obtained. The average amplitude of the Earth’s crustal magnetic field variation in the three elements F, D, and I is 28.5%, 55.4%, and 34.4 of the original results, the MSE is 59.1%, 56.5%, and 40.3% of the original results, and the mean gradient is 93.6%, 91.9%, and 97.0%, respectively. 3. In the processed results of the new method, the seismomagnetic information is clearly optimized, and the location of the epicenter is more consistent with the 0 value line of the Earth’s crustal magnetic field. The processed results of the new method are significantly better than those of the original method and have a higher application value.