geomagnetic data as a precursor of the september 5, 2018 earthquake in japan mw= 6.6

Magnetic anomalies have been discussed long ago as an earthquake precursor. any parameter that changes before the occurrence of the earthquake, so that a precise investigation of these changes could predict the earthquake, is called a precursor. in this study, the characteristic curves are obtained by frequent over plotting of magnetic data in a 24-hour time frame, for three geomagnetic stations and in japan (mmb, kak, kny). all three components (z, y, x) or (z, d, h)were processed in a period of one year. in order to increase the intensity and distinction of the anomalies observed before the earthquake in comparison with the original data, we tried to eliminate the effect of daily variation of the magnetic field by this method.