Rhythmic characteristics of seismic activity in North China and analysis of recent activity stages

According to the seismic data from the North China earthquake statistical area in recent 600 years, time series characteristics of seismic activities in this area and the main seismic zones are analyzed quantitatively by using the maximum entropy spectrum analysis method. The complex alternation of strength and weakness superimposed by multiple dominant periods is observed. The seismic episodes of the North China earthquake zone and the main seismic zones are divided by the Fisher method （optimal segmentation method ） and their characteristics are analyzed. Combined with the analysis of the current seismic quiescence in the North China earthquake region and other phenomena, it is believed that the current seismic trend in this region is at a complex crossroads. North China area may enter a new period of intense seismic activity at any time （it will last for about 10 years） followed by a new period of seismic quiescence （it will last for decades）; There is another possibility that North China has actually entered a new period of seismic quiescence already.