SEISMOLOGY AND GEOLOGY ›› 1980, Vol. 2 ›› Issue (1): 19-26.
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L.M. Jones1, Deng Qidong2, Jiangpy2
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章光月1, 邓起东2, 蒋溥2
Abstract: The earthquake sequence, precursory and geologo-structural background of Haicheng, Tangshan, Songpan-Pingwu earthquakes are discussed in this, article. As we know that all these earthquakes occurred in a seismic zone controlled by the main boundary faults of a intraplate fault block. But the fault plane of a main earthquake is not the same faults rather a related secondary fault. They formed altogether a conjugate shearing rupture zone under the action of regional tectonic stress field. As to the earthquake sequence the foreshocks and aftershocks might be occurred on the conjugate fault planes within an epicentral region rather than limited in the fault plane of a main earthquake, such as the distribution of foreshocks and aftershocks of Haicheng earthquake. The characteristics of the long-, medium- and imminent term earthquake precursory anomalies of the three mentioned earthquakes, especially the character of well-studies anomaly phenomena in the electrical resistivity, radon emission, groundwater and animal behavior, have been investigated. The studies of these earthquake precursors show that they were distributed in an area rather extensive than the epicentral region. Some fault zones in the conjugate fault network appeared usually as distributed belts or concentrated zones of earthquake precursory anomalies, they can be traced in the medium-long term precursory field, but seem more distinct in the short-imminent term precursory anomalous field. These characteristics can be explained by the rupture and sliding originated along the conjugate shear network and the concentration of stress in regional stress field. Moreover, it is worthy to notice the migration of these precursory anomalies along the conjugate rupture zone in the earthquake-brewing process. The macroscopic precursory anomalies of the Songpan-Pingwu and Haicheng earthquakes did not appear first in the epicentral region, but emerged in a set of fault zone conjugated with the fault plane of main earthquake, or in a conjugate fault zone and their intersection region. These phenomena may be originated from the migration of stress-concentrated region and continuous concentration of stress in the earthquake source area. It is also possible that they were progressively initiated at a definite direction along the rupture zone and sliding caused by conjugate faulting.It can be supposed that the effect of conjugate fault on the earthquake brewing and originating process is significant in theoretical studies of seismology and in predicting practice, it should be drawn public attention.
摘要: 根据海城、唐山和松潘-平武地震的地震前兆、地震序列和地质构造资料,提出了在地震孕育和发生过程中,不仅主震断层面有明显的活动,与之共轭的另一组断层面也有重要作用。在震中区,前震和余震可能分布于一对共轭断层面上,而不只是局限于主震断层面。地震前兆的分布范围存在于比震中区更为广大的一个区域内,该区内共轭断层网络中的某些断层带常成为前兆异常分布带或集中区。其形成原因可以用区域应力场中应力集中和沿共轭剪切网络所产生的破裂及滑动来解释。
L.M. Jones, Deng Qidong, Jiangpy. THE IMPLICATION OF CONJUGATE FAULTING IN THE EARTHQUAKE BREWING AND ORIGINATING PROCESS[J]. SEISMOLOGY AND GEOLOGY, 1980, 2(1): 19-26.
章光月, 邓起东, 蒋溥. 在地震孕育和发生过程中共轭断层活动的作用[J]. 地震地质, 1980, 2(1): 19-26.
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