中国及邻区地震的天文潮汐触发特征研究——附加潮汐应力对发震断层的作用模式及其应用
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摘要
本文在潮汐应力、构造应力、地震断层和岩石破裂滑动理论的基础上 ,建立了潮汐应力对地震断层作用的力学模式 ,该模式将潮汐应力与地震应力作用相结合 ,描述了沿地震主压应力和地震主张应力方向的附加潮汐应力对发震断层的力学作用方式 ,从而切入潮汐应力触发地震的物理机制 ,认为潮汐对地震的触发作用在实质上归结为潮汐应力对地震断层的促滑作用 ,这种促滑作用分增压型和减压型。在此模式基础上 ,对中国大陆及邻区的不同类型地震的潮汐触发性进行了研究 ,内容包括 :计算了中国及邻区一千多个地震震源处沿主压应力P轴和主张应力T轴方向的附加潮汐应力分量 ,分析了这些量对发震断层的作用方式 ,按纬度区域统计了受到潮汐应力促滑作用的发震断层类型以及它们与潮汐应力作用方式的关系 ,得到了如下结论 :受到潮汐应力促滑作用的发震断层的比例随区域纬度增加有减小趋势 ,其中 ,走滑型断层的比例在低纬区较大 ,而倾滑斜型断层的比例在中高纬度区较大 ;对整个统计区域而言 ,受增压型潮汐应力促滑作用的发震断层数比例大于受减压型潮汐应力促滑作用的发震断层 ;对不同的纬度区域 ,不同的潮汐应力作用方式与之促滑的发震断层类型也有不同的分布特征。最后 ,本文将中国及邻区受到潮汐触发作用的地震按构造应力?
Based on the theories of the tidal stress, structural stress, seismic faults, rock fracture and slip, the mechanical modal of tidal stress effects on seismic faults is set up. Combining the tidal stress with the seismic stress, the modal describes the ways of mechanical effects on seismic faults by the tidal stress components along the sesmic compressive principal stress and the extensional principal stress. Thereby, the mechanism on tidal triggering of earthquake is touched. The tidal triggering effect on earthquakes actually belongs to the slip acceleration effect of the tidal stress on seismic faults. The patterns of the effect are classified into the compression-adding type and the compression-reducing type. On the basis of the modal, the tidal triggering characteristics of earthquakes in China and its neighbor area are studied. The study includs the following contents. Tidal stress components along the P axis and the T axis of more than one thousand earthquake focuses distributed in China and its neighbor areas are calculated. Patterns of the tidal stress effect on the earthquake faults are analyzed. Statistics of seismic fault types related with the slip-accelerating effect of the tidal stress and the relationship between the types and the patterns are made for various latitude areas. The following features are obtained: Proportion of the numbers of seismic faults related with the slip-accelerating effect of the tidal stress has decreasing trend with latitudinal rising. Among them, proportion of the strike-slip faults in the low latitude area is comparatively large but that of the dip-oblique-slip faults in the middle high latitude area is comparatively large. For the whole area, proportion of the numbers of seismic faults affected by the compression-adding type is larger than that affected by the compression-reducing type. For different latitude areas, various patterns of tidal stress effects and relevant types of seismic faults have various distribution features. At last, the earthquakes in China and its neighbor area suffered by tidal triggering effects are divided according to the structural stress areas. The lunisolar location parameters on the time of the earthquakes are calculated and the distribution patterns of the lunisolar location parameters are obtained.
Based on the theories of the tidal stress, structural stress, seismic faults, rock fracture and slip, the mechanical modal of tidal stress effects on seismic faults is set up. Combining the tidal stress with the seismic stress, the modal describes the ways of mechanical effects on seismic faults by the tidal stress components along the sesmic compressive principal stress and the extensional principal stress. Thereby, the mechanism on tidal triggering of earthquake is touched. The tidal triggering effect on earthquakes actually belongs to the slip acceleration effect of the tidal stress on seismic faults. The patterns of the effect are classified into the compression-adding type and the compression-reducing type. On the basis of the modal, the tidal triggering characteristics of earthquakes in China and its neighbor area are studied. The study includs the following contents. Tidal stress components along the P axis and the T axis of more than one thousand earthquake focuses distributed in China and its neighbor areas are calculated. Patterns of the tidal stress effect on the earthquake faults are analyzed. Statistics of seismic fault types related with the slip-accelerating effect of the tidal stress and the relationship between the types and the patterns are made for various latitude areas. The following features are obtained: Proportion of the numbers of seismic faults related with the slip-accelerating effect of the tidal stress has decreasing trend with latitudinal rising. Among them, proportion of the strike-slip faults in the low latitude area is comparatively large but that of the dip-oblique-slip faults in the middle high latitude area is comparatively large. For the whole area, proportion of the numbers of seismic faults affected by the compression-adding type is larger than that affected by the compression-reducing type. For different latitude areas, various patterns of tidal stress effects and relevant types of seismic faults have various distribution features. At last, the earthquakes in China and its neighbor area suffered by tidal triggering effects are divided according to the structural stress areas. The lunisolar location parameters on the time of the earthquakes are calculated and the distribution patterns of the lunisolar location parameters are obtained.
引文
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