江宁地电台地电阻率日变形态特征与短临畸变异常

ANALYSIS ON DAILY VARIATION SHAPE FEATURE OF GROUND RESISTIVITY AT JIANGNING GEOELECTRIC STATION AND THE SHORT-IMPENDING DISTORTION ANOMALY

江宁地电台使用ＺＤ－８数字地电仪观测以后，记录到了地电阻率测值每日呈准“一峰一谷”的方波形周期变化。本文描述了日周期变化形态，使用时距平方法研究分析了日变化的季节特征和时间特征。在１９９１年９月１２日江宁小丹阳３．１级地震（Δ＝３４ｋｍ）和１９９２年１０月２２日射阳４．６级地震（Δ＝２４４ｋｍ）前，地电阻率日变形态消失，地震１０多天后日变又恢复，出现明显的短临前兆。

The periodic change of ground resistivity,which appears the square wave of‘one peakand one valley ’every day,is recorded by DZ-8 digital terrameter at Jiangninggeoelectricstation.This paper describes the daily period-variation shape,and analyses the seasonalfeatures and temporal features of daily variation by using time-distance square method. Be-fore the Xiaodanyang earthquake,Jiangning(M3.1,Δ=34km)on Sep.12,1991 andtheSheyang earthquake(M4.6,Δ=244km)on Oct.22,1992,the daily variation shape ofground resistivity disappeared,ten plus days after the earthquakes,the daily variation re-covered,showing obvious short-impending precursor.