主震

用A（b）指数判断图象以后有无主震，其效果颇好。

It is effective to decide whether principal earthquake appears after figure by exponent A ( b ) .

土层应变仪观测网的观测结果表明：土层水平最大剪应变在唐山地震前有异常，异常后便发生了主震；

The results observed network by of strainmeters in superficial soils show that the maximum horizontal shearing strain in soils had produced abnormal variation before the 1976 Tangshan earthquake and the principal earthquake would have happened after this abnormal variation .

地震群的形式出现；主震过时，P波初动方向改变。

Direction of primary movement of P wave can change after major earthquake .

我们统计出地震活动条带形成时间与主震主系，总结出条带形成过程中能量蠕变曲线有2种形式以及主震前b值<1。

It is suggested that curves showing the energy accumulation in the course of stripe formation show two patterns and that the b-values before main shock occurrences are smaller than 1 .

用AB连线与主震位置的关系判断未来主震的震中范围

Judgement the epicentral range of coming main shock by the rela-tion of AB linked line and main shock location

此外，还通过P波初动极性分析的方法认为两次主震破裂面的走向略有差别，与余震序列精确定位结果显示的余震区震中分布一致。

In addition , it is also to be found that the strike directions of two rupture zones might vary slightly analyzing initial motion of P wave , coinciding with the relocated results of aftershock zones .

将主震的结果与美国哈佛大学的CMT解进行了对比，结果是非常相似的。

Comparing with the CMT solution of Harvard University , their results are similar .

使用6级地震序列的h值和含主震计算的b值对未来强震震级进行估算，采用5级地震序列的h值和不含主震计算的b值对未来强余震震级进行推算；

Using h value of M6.0 earthquake sequence and b value containing main earthquake to estimate the future strong earthquake magnitude . Using h value of M5.0 earthquake sequence and b value barring main earthquake to estimate the future strong post-earthquake magnitude ;

综上所述，本区破裂过程，主震及Ⅰ、Ⅳ类地震是岩块沿NE及NW向共轭构造的粘滑；

Therefore the fracturing process associated with the main-shock as well as the ⅰ, ⅵ type small earthquakes are stick-slip of rock masses along conjugate faults trending NE and NW .

7次满足CH判据的地震中，除1973年精河6.0级地震发生在其显著地震后63天外，其余主震都发生在其满足条件的显著地震后25天以内。

Of the 7 earthquakes , the main earthquakes occurred 25 days later after its significant earthquakes , excepting the Jinghe M6 . 0 earthquakes occurred 63 days later after its significant earthquakes .

文中作者应用另一相对定位方法双差地震定位法，对张北&尚义地震序列的主震和ML≥3.0余震再度进行精确定位。

In this paper , a relocation of the Zhangbei Shangyi earthquake sequence has been done using the double difference earthquake location algorithm ( DD algorithm ), and consistent results with that obtained by the master event technique were obtained .

发现在主震到来之前，B值和C值会突然上升并持续在高值状态，而熵值H则于此时减小。

It is discovered that the B and C value in a definite region will jump up rapidly and lay in the high position , when the major earthquake is coming . The entropy H of the tide tilt amplitude factor will be reduced in this case .

用释放的地震应变能ε（t）的空间分布特点分析，表明主震前高QC值地区与高应变能释放地区是相一致的。

It is shown from analysis of space distribution of released seismic strain energy ε( t ) that the regions with high Q C value are the regions with high strain release .

主震和余震&从大森公式到ETAS模型

Main Shock and After Shock & From the Omori Formula to the ETAS Model

通过对地震震源拐角频率fc及地震应力降Δσ随时间变化的统计分析，本文研究结果发现，施甸5.9级主震前的前震序列地震的平均拐角频率明显低于主震后余震序列的平均拐角频率。

Through the statistical analyses of variation of corner frequency f_c and stress drop Δσ with time , it is discovered that the average corner frequency of the foreshock sequences is obviously lower than that of the aftershock sequences .

此外，主震表现出高破裂速度特点，与Inglewood断层为成熟断层的特征一致。

The high rupture velocity may be related to the fact that the Newport-Inglewood fault is a mature fault .

在95%置信概率下，考虑主震破裂形式，分序列类型给出了余震分布尺度与M0之间的统计关系。

Considering the rupture mode of the main shock , we give the quantitative statistical relationships between R and M0 under 95 % confidence levels for different sequence types .

结果表明，主震前后区域尾波振幅衰减率β和QC-1值发生了明显的变化。主震前，区域平均β值为00122s-1，相应的QC值为111；

The results show obvious variation in the β and Q C - 1 values of regional coda wave amplitude attenuation rates before and after the main earthquake .

对比研究显示，当M0较高时，余震分布尺度主要取决于主震大小而与主震破裂形式关系不明显。

Comparing with previous results , it indicates that , when M0 is large enough , R is mainly determined by M0 and there is almost no relationship with the rupture mode of the main shock .

震前有信号震的比例占92%，83%的信号震距主震150km以内，距主震发生时间小于1年的占67%。

92 % of earthquakes were followed signal earthquakes , and 83 % of these signal earthquakes are within distance of 150 km from the main earthquakes and 67 % of which were followed by main earthquakes occurred in less than a year .

1976年唐山地震为三主震型地震

The Tangshan earthquake of 1976-an event of triple main shock pattern

利用邢台直接前震预报主震

The prediction of the Xingtai main shock by the direct foreshocks

平直构造为主震&弱余震型；

The flat straight fault leads to mainsheck weak aftershock type ;

并认为岫岩5.4级主震可能被前震触发，这为主破裂成核过程提供了一次实例。

It gives one example of the earthquake nucleation process .

双震型序列第二主震的预测指标研究

Study of prediction indices for second main earthquake of double earthquake sequence

波速比异常空间演化与主震位置预测

Spatial evolution of wave velocity ratio anomaly and prediction of main earthquake location

余震在主震和最大余震之间活动；

Aftershock activity between main shock and maximum aftershock ;

其总的迁移范围及迁移方向与主震破裂方式有关。

The distance and direction of migration are related to the rupture pattern .

结果认为此次地震为主震余震型。

The result considered that the earthquake belongs to main shock aftershock type .

这种预测方法认为地震空区将是大地震的主震区。

This theory postulates that such places are due for a major shock .