自六十年代中期开始,国内外对强震前出现地震活动空区现象的研究日益增多,也成功地根据空区观象预报了某些强震。但是,已报道的众多震例中,空区的形态、尺度及其形成时间很不相同,也很少给出判定地震空区的标志。甚至对同一个地震,不同的作者可能给出很不相同的几个空区,如图1 所示。 Since the mid-1960s, there has been a growing number of studies on the phenomenon of vacant seismicity before strong earthquakes at home and abroad, and some strong earthquakes have been successfully predicted based on the observation of vacant areas. However, in many earthquake cases that have been reported, the shape, scale and time of formation of vacant areas are very different, and the marks of judging the area of ​​seismic areas are seldom given. Even for the same earthquake, different authors may give quite a few empty spaces, as shown in Figure 1.