强震前地震活动图象与震源机制类型的相关性分析
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摘要
在对1966年以来63次强震前中等地震活动图象全时空扫描的基础上,讨论了大陆不同构造区域、不同震源机制强震前中等地震活动图象异常演化特征及其主要活动图象与震源机制节面的相关性.研究表明:强震前中等地震活动图象显现出应力集中和减弱两个阶段性特征,第一阶段(中期阶段)的活动图象以条带、空区和集中活跃为主;第二阶段(中短期)以持续平静为主.走滑和正断层机制震前显示出较好的特征图象;逆冲断层震前的活动图象与其它两种机制的图象不同,没有明显的特征图象,两个阶段都有平静现象出现.强震前中等地震条带走向与震源机制的两个节面走向一致性较好,但空区的一致性较差.
On the basis of the results from spatial-temporal scanning of moderate seismic activities prior to 63 strong earthquakes occurred since 1966, we investigate in this paper the characteristics of anomalous evolution of moderate seismic activities prior to strong earthquakes with different focal mechanisms in different tectonic blocks, as well as the correlation between principal seismic activities and nodal planes of focal mechanisms. The research results indicate that the moderate seismic activities prior to strong earthquakes display two significant stages of stress concentration and stress weakening, which are consistent to the evolvement of local tectonic stress field. The first stage, defined as medium-term stage, is characterized by seismic belts, seismic gaps and centralized activities; the second stage, defined as the short-term stage, is predominated by continuous quiescence. For the earthquakes occurred on the strike-slip and normal faults, the two stages are relatively evident; while for the earthquakes occurred on the thrust faults, there is no characteristic images and seismic quiescence appear in both stages. The spatial distribution of moderate shock belts before strong earthquakes show a good coherence with that of the two nodal planes of focal mechanisms, while the spatial distribution of seismic gaps enclosed by moderate shocks display a poor coherence with the nodal planes.
On the basis of the results from spatial-temporal scanning of moderate seismic activities prior to 63 strong earthquakes occurred since 1966, we investigate in this paper the characteristics of anomalous evolution of moderate seismic activities prior to strong earthquakes with different focal mechanisms in different tectonic blocks, as well as the correlation between principal seismic activities and nodal planes of focal mechanisms. The research results indicate that the moderate seismic activities prior to strong earthquakes display two significant stages of stress concentration and stress weakening, which are consistent to the evolvement of local tectonic stress field. The first stage, defined as medium-term stage, is characterized by seismic belts, seismic gaps and centralized activities; the second stage, defined as the short-term stage, is predominated by continuous quiescence. For the earthquakes occurred on the strike-slip and normal faults, the two stages are relatively evident; while for the earthquakes occurred on the thrust faults, there is no characteristic images and seismic quiescence appear in both stages. The spatial distribution of moderate shock belts before strong earthquakes show a good coherence with that of the two nodal planes of focal mechanisms, while the spatial distribution of seismic gaps enclosed by moderate shocks display a poor coherence with the nodal planes.
引文
[1]来自http://www.seismology.harvard.edu
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许忠淮,汪素云,黄雨蕊,等.1989.由大量的地震资料推断的我国大陆构造应力场[J].地球物理学报,32(6):636~647
张国民,傅征祥,桂燮泰,等.2001.地震预报引论[M].北京:科学出版社,12~22,351~357
邓起东,张培震,冉勇康,等.2003.中国活动构造与地震活动[J].地学前缘,10(特刊):66~73
华祥文.1980.唐山强震前后北京、天津周围地区应力场的变化过程[J].地震学报,2(2):130~146
胡小幸,林邦慧.1989.邢台地震空间分布随时间变化的立体图象与地震发生的过程[J].地震学报,11(1):1~11
林邦慧,魏福胜,刘万琴.1982.溧阳—介休—五原北西地震带强震的破裂特征[J].地震学报,4(2):116~126
林邦慧,陈天长,蒲晓红.1986.鲜水河断裂带强震破裂过程与地震活动[J].地震学报,8(1):1~20
林邦慧,胡小幸,周冉.1989.强震震源破裂过程、地震震源参数与地震活动[A].见:国家地震局地震监测司编.地震预报方法实用化研究文集:地震学专辑[C].北京:学术期刊出版社,409~425
梅世荣,冯德益,张国民,等.1993.中国地震预报概论[M].北京:地震出版社,323~324
秦保燕,谭爱娜,李亚荣.1990.动态应力与地震图象变化的相关性初探[J].内陆地震,4(3):201~210
王辉,张国民,江在森,等.2005.利用多种地震学参数研究中国大陆地壳应变场[J].地震,25(2):9~18
许绍燮.1989.以物理模型为基础的概率性地震预报方案[A].见:国家地震局地震监测司编.地震预报方法实用化研究文集:地震学专辑[C].北京:学术期刊出版社,554~575
许忠淮,汪素云,黄雨蕊,等.1989.由大量的地震资料推断的我国大陆构造应力场[J].地球物理学报,32(6):636~647
张国民,傅征祥,桂燮泰,等.2001.地震预报引论[M].北京:科学出版社,12~22,351~357
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