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

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.