定点形变前兆异常起始时间的判别

本文运用差分法、灰色动态滤波、有限富氏级数拟合、契比雪夫多项式拟合等四种方法，同时对１９８４年５月２１日南黄海Ｍｓ６．２级和１９８７年２月１７日射阳Ｍｓ５．１级地震前后时段内的数据资料进行处理，以莱以特准则和格罗布斯准则对处理后的残差序列进行异常超始时间的判别，并对比和综合分析。两种准则相比较，格氏判别在数学上更加严密，结果更为可信。初步研究表明，中强震在震级较高的情况下，用两种准则判别的结果比较接近，而在震级较低的情况下两者判别结果有差异。综合判别结果与总结本地区中强震震例给出的相关经验公式之计算结果相近。

THE DETERMINATION OF BEGINNING TIME OF PRECURSORY ANOMALIES FOR FIXED POINT DEFORMATION

In this paper,the biginning time of precursory anomaly is determined for the residual sequence of fixed point deformation data with the Laiyite and Grubbs criterions. By the methods,such as difference,grey dynamic filtering,limited Fourier fitting and Chebyshev polynome fitting,the preseisimc and postseismic deformation data of the south Yellow sea earthquake(Ms 6.2)on May 21,1984 and the Sheyang earthquake (Ms 5.1) on Feb.17,1987 are preprocessed. Through comparison and compr-hensive analysis based on the results computed,it is clear that the Grubbs criterion is more strict than the Laiyite criterion.It is proper that we can make a plan for short-impending earthquake tracing on basis of anomaly found effectively using both above criterions. Elemantary study shows that the determinations with both criterions for large event are close to each other but different for smaller event and the results of comprehensive determination are about the same to those results obtained with empirical relations between medi-strong earthquake magnitude and the anomaly duration in the area.