THE ANALYSIS FOii THE PRECURSORY EFFECT CHARACTERISTICS OF WATER DYNAMIC VARIATION IN THE SALT WATER LAYER IN TIANJIN

The precursory effect characteristics of the salt water level in the developing process of the Tangshan earthquake, such as anomalous drop with Hie different ratio in the early period, the inverse rise in imminent stage and the sharp rise in the coseismic period, have been described. However, according to the measuremnt and observation data in the salt water layer, it is shown that the salt layer has a good confining property which is the structure condition for causing the precursor change in the salt water level and the distribution of the salt water layer closely near the southwestern side of the Tangshan earthquake source zonc is the forced condition which causes the precursory change of salt water level. By the comparision among the actural observartion data and computed results, the salt water layer can reflect the micro- and shorl-strees variation, by which the caused change ia salt waierl level is particular in sharp and too small to affect the identification for the precursor phenomena of the salt water level. Inversely, it is quoted that the rise and drop variations in the salt water level must be resulted in under the tectonic force in the developing process of the moderate strong earthquake, Finally, the premonitory process of the salt wafer level has been described.