The Characteristics of Information Dimension

<正> Based on the information theory and multifractals viewpoint, the information dimension D1 of acoustic emission （AE） of rock for marble, gabbro and sandstone ina laboratory condition and seismic activities before and after some large earthquakes are studied. The results show that there is a dimension reduction process before the failure of rock and before the occurrence of large earthquakes. The curves of D1 determined during the process have a wider non-scaling range. Moreover, the non-scaling range became narrow when rock was close to failure fracture and large earthquake was just to happen. This showsthat the system has instable criticai behavior.