中国大陆若干地震构造带的地震准周期丛集复发行为

QUASI-PERIODICALLY CLUSTERING EARTHQUAKE RECURRENCE IN SOME SEISMOTECTONIC BELTS OF CHINA CONTINENT

以青藏高原东南缘和东北缘若干地震构造带的历史地震活动资料为基本数据 ,通过地震复发间隔的计算、分类和统计检验等 ,研究了大陆板内地震的复发行为。认为 :大陆板内地震既不是简单地准周期重复发生 ,也不是简单地丛集复发 ,而可能是一种准周期的丛集复发行为 ,即地震丛是准周期重复发生的 ,而在某一地震丛内 ,地震又是丛集复发的。存在两类地震复发间隔 ,即地震丛复发间隔和地震丛内的地震复发间隔 ,它们分别满足对数正态分布和指数分布。在进行大陆板内活动断裂地震危险性定量计算和评估时 ,不能简单地套用 N.B.实时模型中给出的地震复发间隔概率密度函数或累积分布函数 ,而应该根据当前地震的活动水平 ,判断当前是属于丛内的活跃期还是丛间的平静期 ,据此分别选用地震丛内地震复发间隔分布函数或者地震丛复发间隔分布函数 ,这样将大大提高活动断裂地震危险性计算和定量评估的水平。最后 。

By analyzing the seismicity of several seismotectonic belts around the southeastern and northeastern margins of Tibet Plateau,this paper studies the recurrence behavior of intraplate continent earthquakes.It is concluded that the earthquakes of intraplate continent do not recur just quasi periodically or just in a cluster,but recur in a quasi periodical cluster.That is to say that earthquake clusters recur quasi periodically,and earthquakes among an earthquake cluster recur in a cluster.Hence there exist two types of recurrence interval recurrence interval of earthquae clusters and recurrence interval of earthquakes among an earthquake cluster,they satisfy lognormal distribution and exponential distribution respectively.When analyzing and assessing the seismic potential of active faults in an area,we can not simply use the distribution function of earthquakes recurrence intervals given by N.B.Model.We should select the distribution function of earthquake cluster recurrence interval or distribution function of recurrence interval of earthquakes among an earthquake cluster respectively according to the area's current seismicity:still in an earthquake cluster or at the beginning of a new earthquake cluster?This way the accuracy of seismic hazard assessment will significantly be improved.Finally,the possible physical mechanisms for the quasi periodically clustering recurrence of intraplate earthquakes are briefly discussed.