华北八次强震前区域地震单位平均能量迁移速率变化特征

FEATURES OF AVERAGE EMERGY MIGRATION RATES BEFORE 8 STRONG EAPTHQUAKES IN NORTH CHINA

在强震发生前，发现平均能量迁移速率ＶΔＴ值是减少的。华北地区八次强震中有六次震前出现低值异常，有五次地震发生在ＶΔＴ最低值出现并恢复后的一年左右。整个ＶΔＴ低值异常持续时间和幅度与未来震级无明显的对应关系。笔者认为ＶΔＴ是与介质的时间平均强度相应的，与地震活动的时、空分布图象有相应关系的特征量。

It is discovered that the average energy migration rates V△T before strong earthquakes decrease.There were low value anomalies before 6 strong earthquakes that out of 8 strong earthquakes in north China. 5 strong earthquakes happened about a year late at the time that V△T minimum value had appeared and recovered. Dyrations of VΔT low value anomalies and amplitudes are not corresponding to the forthcoming earthquake magnitudes. It is considered that VΔT is a characteristic quantity which relates to medium strength and space - time distribution patterns of seismicity.