1999年9月21日台湾发生7.6级地震群，震时长沙井水位记录到了水震波和水位阶图象。本 文分析了水震波及水位阶产生的机理，认为：震时地震应 力波作用于含水层，使含水层的流体压力及有效应力发生变化，周期作用的应力波是井口水 位产生震荡变化的原因；而有效应力变化导致岩石骨架胀缩及岩石颗粒重排，岩石骨架胀缩 的不可逆及塑性变形部分和岩石颗粒重排是造成震时水位阶的原因，其中，岩石骨架压 缩引起的水位阶在震后可以部分缓慢恢复。%While the MS7.6 Jiji earthquake swam on Sept.21,1999 was occurring,the ground water level vibration and leap was recorded by the water level instrument at Changsha well.Based on the power balance principle of well-aquifer system,the me chanism of the water level vibration and leap has been analysed in this paper.Th e results show that the seismic stress wave acted on the aquifers lead to a chan ge of the fluid pressure and effective stress;periodic acting stress wave result ed in water level vibration.The change of the effective pressure make the rock i n bed of the aquifer dilatation and compression,also lead to the grains of rock re-arrangement.Those irreversible and plastic deformation in the course of the d ilatation-compression and rock's grains re-arrangement made the water leve l leap. Among them,the water level leap resulted from the plastic deformation ca n partly recover after earthquake.
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