| 伽师序列中小地震震源机制分析 |
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| 引用本文： | 刁桂苓,高国英,聂小红,龙海英,王海涛.伽师序列中小地震震源机制分析[J].国际地震动态,2007(12):1-9. |
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| 作者姓名： | 刁桂苓 高国英 聂小红 龙海英 王海涛 |
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| 作者单位： | 1. 河北省地震局,石家庄,050021
2. 新疆维乌尔自治区地震局,乌鲁木齐,830011 |
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| 基金项目： | “十一五”国家科技支撑计划重点课题《强震动力动态图像预测技术研究》(基金项目编号为2006BAC01B02-01-01)) |
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| 摘 要： | 采用点源位错模型,层状介质速度结构,通过计算理论地震图,与观测的地震垂直向记录的直达P、S波最大振幅拟合,反演震源机制的方法。系统查阅了万余张地震记录图件,得到可信的小地震震源机制共计554个。有震源机制的地震完全覆盖了序列的震区范围,时间上也分布于序列的各个阶段,因此认为这些小地震对于地震序列具有一定的代表性。计算2个震源机制的2个P轴在三维空间中的夹角和2个T轴之间的夹角,再以2个夹角之和作为距离,采用系统聚类的方法对大量地震震源机制解进行分类。取和主体破裂方向(NE)一致的两类正断层地震,求其占全部类型的地震数目的比例,用来刻画应力场的变动情况。对照伽师序列的6级强震,两类正断层地震出现3次显著的增加。3组强震都在其后发生,这就给出了确切的前兆信息。小地震震源机制显示出的变化,表明它们对于强震孕育发生非常灵敏。文章最后提出伽师强震序列的块体旋转成因模型。
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| 关 键 词： | 伽师地震序列 中小地震震源机制 地震前兆信息 序列块体旋转成因模型 |
| 收稿时间： | 2007-02-25 |
| 修稿时间： | 2007年2月25日 |
Analysis on the Focal Mechanism of Small and Medium Earthquakes in Jiashi Sequence |
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| Diao Guiling,Gao Guoying,Nie Xiaohong,Long Haiying,Wang Haitao.Analysis on the Focal Mechanism of Small and Medium Earthquakes in Jiashi Sequence[J].Recent Developments in World Seismology,2007(12):1-9. |
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| Authors: | Diao Guiling Gao Guoying Nie Xiaohong Long Haiying Wang Haitao |
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| Abstract: | Using the dislocation model of the point source and layered velocity structure in crustal medium,through computing the theoretical seismic seismograms,we synthesized the maximum amplitude of P and S wave in vertical components with the observation earthquake in order to inverse the focal mechanism.About ten thousands of earthquake record have been studied,and 554 focal mechanism solutions of credible small earthquakes are obtained.The earthquakes with the focal mechanism solution cover completely the seismic region of the sequence.It has also distributed in all time duration in the sequences.So we think that these small earthquakes can be represented for the whole sequence.We calculate the angles between the P axis and the T axis of two focal mechanism solutions in 3 dimensions,and take the sum of two angles as the distance.By using the system cluster method,the classification of focal mechanism solutions has been carried out.We chose two types of normal fault which is consistent with the main fracture direction(NE).And compute the proportion of earthquake numbers in all types.Then,using it to reflect the change of the stress field.Comparing the type of M6 earthquakes in Jiashi sequence,two types of the normal fault earthquakes occur remarkablely before M6 earthquakes.It seems the change of the focal mechanism of the small earthquake may indicate some precursory meanings.Finally,the model of the block body revolving for the Jiashi strong earthquake sequence has been suggested. |
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| Keywords: | Jiashi earthquake sequence focal mechanism of small and medium earthquakes precursory information of earthquakes earthquake model |
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