Rydelek-Sacks test for the periodicity distinguishing of northeastern China earthquakes and study on their magnitude-time periodical spectrum

For distinguishing the potential periodicity and the relationship between shallow and deep earthquakes in northeastern China, this paper conducted the Rydelek-Sacks test based on various earthquake catalogues to consider the influence of selected magnitudes on the periodicity. The test for the periodicity distinguishing was investigated by using shallow earthquakes from 1970 to 2009 with magnitude no less than ML4.5, 1920 to 2009 with magnitude no less than MS5.0 and deep earthquakes from 1905 to 2009 with magnitude no less than MS6.0. Major results of our study are: ① Deep earthquakes in northeastern China region have an obvious and stationary active period; ② Periodicity of shallow earthquakes probably depends on magnitude; ③ Good correlation between deep earthquakes and ML4.5mdash;5.0 shallow ones show that in northeastern China deep earthquakes may influence on the shallow earthquakes with magnitude even lower than MS5.0. This fact is beyond our traditional knowledge.