常熟—太仓地震的地下水异常场及其启示

本文对常熟—太仓地震前丰富的地下水异常进行了描述,并对异常场的时空演变及其预报意义进行了分析,指出:最早形成且时空集中的突出异常区,当异常外迁后又向原地区回迁,意味着发震地点、时间的逐渐逼近,就此次震例与现有认识不同的一些特点,提出如下新认识: 1、当区域应力明显增强,观测网密度又高,而地区震级有一定“上限”时,异常规模与震级不一定相“匹配”。 2、区域应力的脉冲式变化,可使地下水产生类似临震异常的阵发性大幅度变化,使得异常活跃程度与异常阶段不一定相“匹配”。 3、水温异常很有潜力,但机理复杂,应同时注意“微观”与“宏观”尺度的水温异常。

THE ANOMALOUS FIELD OF GROUNDWATER BEFORE THE CHANGSHU-TAICANG EARTHQUAKE AND ENLIGHTENMENTS

In this paper. a plentiful anomaly or groundwater before the Changshu earthquake occurred is described, and the time and space variation of the anomalous field and its significance for earthquake prediction is analyzed. In the area of prominent anomalies which were earliest formed and clustered in time and space, the back immigra- tion of anomalies after out immigration implies an approach to the time and location of an earthquake occurred. Based on some features of this earthquake, the new views are sug- gested as follows: 1.When regional stress is obviously increased, the density of observation network is high and the local magnitude has certain "upper limit", the scale of anomaly is not necessa- rily matched with the magnitude. 2.The pulse variation of regional stress may bring about the sudden variation of groundwater with large amplitude which is similar to the immediate anomaly of earthquake, so that the active degree of anomaly is not necessarily matched with the anomaly stage. 3.The temperature anomaly of groundwater has the potential of earthquake predic- tion, but its mechanism is complicated. The temperature anomaly of groundwater must be attended in both "microscopic" and "macroscopic" scale.