台湾海峡7.3级地震余震活动的月相效应

利用福建地震月报目录,对1994年 9月16日台湾海峡南部M_S 7.3地震的余震活动月一定震级以上的频次进行统计的结果表明,台湾海峡余震活动在一个朔相效应进行了研究。对望月内的变化是有起伏的,起伏明显地受月相的调制,起伏的变化在朔、望、上下弦附近出现相对极值,并且频次起伏的幅度可达地震活动平均频次的80%以上,从而证明了余震活动的月相效应是明显存在的,其影响是不可忽略的。另外,通过对月相效应的谐波分析还表明,余震月相效应的基本特征是具有1/4月波和半月波的周期性。研究余震活动的月相效应对强余震的预报 及其区域应力场的变化有一定的科学意义和实用价值。

THE EFFECT OF LUNAR PHASE ON AFTERSHOCK ACTIVITY OF TAIWAN STRAIT EARTHQUAKE WITH M_s7.3

By applying monthly earthquake catalogue reported from Fujian, this paper studiedthe effect of lunar phase associated with aftershock activity of Taiwan Strait earthquakewith Ms7. 3, which occurred on 16 Sep. 1996- The statistic results on frequency of earth-quakes with a certain magnitude show that the changes of aftershock sequence in TaiwanStrait within the synodic month are fluctuated l and the fluctuation is obviously modulatedby the lunar phase. The change of fluctuation reaches the relative limitation around thenew moon, full moon, first and last quarters, while the amplitude of the frequency fluctu-ation can be as much as more than 80 percent of the average frequency of seismicity. All ofthese facts proved the existence of the lunar phase effect of aftershock activity l and this in-Fluence can't be neglected. Additionally, the results of harmonic analysis of the lunarphase effect also show that the lunar phase effect of aftershock sequence is characteristic ofthe periodicity of one fourth month and half month- It is scientifically meaningful andpractical to study the lunar phase effect of aftershock on strong aftershock prediction andthe change of regional stress field.