Earthquake Magnitude-Frequency Relationship and Earthquake Magnitude Prediction in North China

The magnitude-frequency relationships of earthquakes of magnitude M L 2.0 or higher in North China, Shandong and neighboring areas since 1970 are calculated, and the long-term and annual-scale seismic intensities are analyzed. The maximum intercept magnitude and the annual-scale seismic intensity are M L 7.5 and M L 5.5, respectively, in North China within a long time frame. The three-year-scale time scan predicts that the maximum intercept magnitude and the seismic intensity in 2022 will be M L 5.3 and M L 4.8. In contrast, the maximum intercept magnitude and the annual seismic intensity in Shandong and neighboring areas are M L 6.2 and M L 4.5, and the three-year scale time scan predicts the corresponding values in 2022 will be M L 4.8 and M L 4.2, respectively. The predicted maximum earthquake magnitude in Shandong in 2022 has a high probability (63%) of not exceeding M L 4.8. Furthermore, the theoretical annual average occurrences and recurrence interval for each earthquake magnitude in Shandong and neighboring areas are calculated, with an average of 30 earthquakes per year for magnitude 3.0, 3.1 earthquakes per year for magnitude 4.0, once every 3.1 years for magnitude 5.0, 29 years for magnitude 6.0, 282 years for magnitude 7.0, and 2713 years for magnitude 8.0. The maximum intercept magnitude in North China has gradually weakened in the past 50 years, yet this tendency is not obvious in Shandong. It is noteworthy whether this indicates seismic activities in North China have gradually entered a quiet period.