【摘要】 将全球分为15个研究区,用1900～2009年M_W≥7.0地震目录,统计分析了各区大地震与月球交点运动周期的关系,得出15个研究区中有10个区,大地震存在统计意义上的18.6 a周期:活跃段为12.4 a,平静段为6.2 a;环太平洋地震带北、南、西、东4大区的大地震,不仅有这样的周期,而且其地震活跃段的时间存在一定规律.用第6个18.6 a(1991～2009年)期间的大地震,检验据前5个18.6 a(1900～1990年)地震目录所得18.6 a周期的稳定性和实用性,发现有这种周期的地区多数的周期性是稳定的.大地震18.6 a周期的可能成因有:(1)18.6 a潮波通过调制日潮和半日潮调制大地震;(2)上地幔内流体的潮汐(地内潮)作用;(3)18.6 a潮波通过影响地球自转变化调制大地震.更多还原

【Abstract】 Dividing the world into 15 study areas and using the earthquake catalogue of M_W≥7.0 during 1900 ～ 2009,we make a statistical analysis of the relationship between seismicity of each area and the period of lunar nodal motion.The result shows that among the 15 areas,10 areas exhibit an 18.6-year cycle of great earthquakes in statistical sense,which consists of a 12.4-year active section and a 6.2-year quiet section.In the eastern,northern,southern and western areas of the Circum-Pacific seismic belt,such a periodicity is present and their active sections have certain regularity.In terms of seismic events during the sixth cycle (1991～ 2009),this study has tested the stability and applicability of the 18.6-year periodicity derived from earlier five cycles (1900～ 1990).It is found that most of periodicities are stable in the regions with such characters.The possible mechanisms of the 18.6-year periodicity are as follows:(1)Earthquakes are modulated by the 18.6-year tide via day and half-day tides.(2)Effect of fluid tide in upper mantle (tide within the Earth).And (3)earthquakes are dictated by 18.6-year tide through variation of Earth rotation.更多还原