The years whether Ms≥7.0 earthquakes occurred or not are investigated by using the Ms≥5.0 earthquake catalog occurred in the Chinese mainland. The year when an Ms≥7.0 earthquake occurred is called "earthquake year", and the year when no Ms≥7.0 earthquake occurred is called "no-earthquake year". The relationships between the annual numbers of Ms≥5. 0 earthquakes and "earthquake year" or "no-earthquake year" are analysed, and χ2 test method has been employed to test the significance. The results obtained are as follows; ① If the annual nember of the Ms≥5. 0 earthqaukes is greater than 30 in some year, the sixth year later is "no-earthquake year". The test of significance for this relationship can be passed under the significance level of 2 percent; ② If the annual nember of Ms≥5.0 earthqaukes is greater than or equal to 24 in some year, the sixth and ninth years later are "no-earthquake year". The tests of significance for these two relationships can be passed under the significance level of 10 and 2 percent respectively; ③ If the annual nember of Ms≥5. 0 earthqaukes is less than 10 in some year, the sixth year later is "earthquake year". The test of significance for this relationship can be passed under the significance level of 2 percent.%利用中国大陆1930年以来的5级以上地震目录,以年为单位统计7级以上地震,只要某年发生了7级以上地震就视为“有震年”,不区分该年发生了多少次7级以上地震,若某年没有发生7级以上地震就视为“无震年”.分析5级以上地震年频次与“有震年”或“无震年”之间的关系,利用x2检验方法对其显著性进行检验.结果表明:①当5级以上地震年频次N＞30时,其后第6年为“无震年”,这个关系在2％的显著水平下通过显著性检验；②当5级以上地震年频次N≥24时,其后第6年或第9年为“无震年”,这个关系分别在10％和2％的显著水平下通过显著性检验；③当N＜10时,其后第6年为“有震年”,这个关系在2％的显著水平下通过显著性检验.
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