唐山地震区的地壳形变及强震重复时间预测

CRUSTAL DEFORMATION AND REPETITION INTERVAL PREDICTION OF STRONG EARTHQUAKES IN TANGSHAN SEISMIC AREA

无论是地震前，还是地震后，在国内所有大震区中，唐山地震区的垂直形变资料都是最丰富的。作者在研究这些资料以后发现，唐山地震区的地壳形变，在1967年以前经历了相当长的缓慢匀速的变化过程，1967—1969年全区出现了加速上升，紧接着转为快速下降和不稳定变化，根据宁河的流动水准测量资料推测，临震前地震断层发生了无震蠕动。大震发生时，全区出现了大幅度的同震形变。大震发生之后，地壳形变的速率随着余震的衰减而呈对数形式衰减。到1988年为止，形变速率已基本降到正常水平。据此估计，今后唐山地震区发生6级以上强余震的可能性不大。

Crustal deformation in Tangshan area had come through a slow and uniform speed variation for a quite long time before 1976, and showed an accelerating rising in the whole area during 1967-1969,then turned to a rapid descent and unsteady variation, the phennomenon of fault creep-slip of nonearthquake was discovered by Ninghe leveling. Coseismic crustal deformation with large amplitude appeared in the whole area when the large earthquake occurred. The speed rate of crustal deformation attenuated in the form of logrithm with after -shock attenuation after the large earthquake. The speed rate of crustal deformation had recovered to its normal level until 1988. The authors estimated the occurrence possibility of strong after-shocks with Ms≥6. 0 is not big for the future.