2003年11月13日岷县ML5.5级地震震源机制的矩张量反演

利用2003年11月13日岷县5.5级地震震中周围7个台站的数字记录反演了本次地震的矩张量,对所得结果与用P波初动符号的结果进行了比较,二者具有较好的一致性。结合该地区的地震分布和本次地震的余震分布,对可能的发震断层进行了讨论。     

Moment tensor inversion of some aftershocks of the April 18, 1985 Luquan earthquake of Yunnan Province, China

Based on the three component accelerograms, recorded at near-field distance by a temporary seismic network consisting of digital cassette tape recording accelerographs, the focal mechanisms of three aftershocks of the April 18, 1985, Luquan, Yunnan Province, China, earthquake ofM _S=6.1, are calculated using seismic moment tensor inversion technique. The phases of direct P, S and converted SP waves in the displacement seismograms, produced by twice integrations of the observed accelerograms, are identified via forward calculation using Green’s functions for homogeneous semi-infinite elastic medium, and used in the inversion. The results of inversion show that a better fit of synthetic to the observed seismograms of direct as well as converted phases can be achieved if appropriate weighting functions are used in solving the over definite linear equations. While these aftershocks are of different magnitudes (M _L=4.8, 3.2 and 3.5, respectively) and hypocentral locations, their focal mechanisms are very similar and consistent with that of the main shock. This feature demonstrates the intrinsic correlation between the occurrence of aftershocks and the seismogenic fault of main shock. Our experimentations show that using the near field accelerogram obtained from the digital seismic network with appropriate azimuthal coverage on the focal sphere, with the aid of even simple medium model, not only the shear dislocation source, but also the isotropic part and CLVD (compensated linear vector dipole) can be retrieved by the technique of moment tensor inversion. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 412–419, 1991. This work is supported by the Chinese Joint Seismological Sciences Foundation and the Western Yunnan Earthquake Prediction Test Site (WYEPTS), State Seismological Bureau.     

关于大地电磁的静校正问题

本文从理论上严格地论述了大地电磁测深曲线静态位移的原理,简单介绍了目前国内外所采用的静校正方法,并着重分析了我们所用的压制表层电性不均匀干扰的办法及其效果。     

地壳介质各向异性电性本构关系讨论

讨论了地壳介质中常见的两类电性各向异性。推导了长波长条件下薄中向异性电导率张量;提出了一种新的电导率物理模型并由此推导了与ＥＤＡ裂隙相适应的各向异性电导率张量。从直流电法和大地电磁测深法的角度分别讨论了这两种电性各向异性所显现的地表视电阻率、阻抗和电位特征。     

摩擦材料的位移间断条件研究

应用势能变分原理导出了位移间断条件,它仅与材料的强度有关。同时也建立了位移间断条件与控制方程解丧失唯一性之间的联系,探讨了两者之间的异同,明确了两者等效的范围。研究结果表明：解的唯一性丧失是应用本构算子和声学张量来讨论材料刚度劣化造成的稳定问题,其条件应该等效于位移间断条件,但它没有用强度条件表示的位移间断直接,尤其是在材料的试验破坏强度明确时。     

由多个震源机制解分析甘肃及边邻地区应力场特征

基于震源断层面解的空间取向和断层滑动方向,由相应力轴张量在地理坐标系中的表达式,通过坐标旋转、代数平均可求得多个震源机制解的P、B、T轴参数的平均应力场。据甘肃及边邻地区的分区活动特征,将研究地区分为8个小区域,由各个区域内多个地震震源机制解,采用力轴张量计算法,得到了各个区应力张量的定量分析结果。