Abstract: The geomagnetic daily ratio anomaly plays an important role in earthquake prediction in Xinjiang, China, but the spatial relationship between the abnormal current source and the earthquake is not clear. In this paper, nearly 30 geomagnetic daily ratio anomalies and more than 40 subsequent corresponding earthquakes in the middle and western sections of the Tianshan Mountains in Xinjiang since 2015 are used. Based on the Biot-Safar theorem, the relationship between the current source of the geomagnetic daily ratio anomaly in Xinjiang and the earthquake is analyzed. The following conclusions are obtained: ① Compared with the currently used area enclosed by the threshold line as the earthquake prediction area, the area enclosed by the anomalous current line is generally smaller than the threshold line, and the predicted area in the middle section of the Tianshan Mountains is reduced by 64.8%. The anomalous current line can significantly reduce the area of the prediction area. ② From the spatial relationship between earthquakes and abnormal current lines, more than 50% of the epicenters are closer to the abnormal current lines, and the distance between earthquakes and current lines in the middle of Tianshan Mountains is reduced by 57.7% compared with the threshold line. The earthquakes in the western section of the southern Tianshan may be more likely to occur at the end of the abnormal current line and its extension line, while the middle section of the Tianshan does not show a clear dominant seismogenic area. ③ Earthquakes with magnitude above 6 are prone to occur at or near the intersection of multiple daily abnormal current lines. The above results show that the geomagnetic diurnal variation anomaly source current positioning method can effectively reduce the prediction area in Xinjiang, China, and the research is conducive to further improving the existing prediction indicators.

Key words: Daily ratio of geomagnetism, Earthquake, Current