Abstract: In the study of strong earthquake cycling and periodicity, the sample size of strong events often influence and even limit the reliability and result extrapolation, especially when strong earthquake activity is low, there will be large uncertainty in state judgement. Small-moderate earthquake activity in the seismogenic process of strong earthquakes actually reflects the characteristics of strong earthquake activity. In this article, we analyse the state of strong earthquake activity based on seismic information entropy of weibull distribution for west China continent. The result shows that the entropy value in the west area is low at present, which may mean that the west area is going to enter a new active period of strong earthquakes and the risk site may be in the Qingzang tectonic block. In the same scanning condition of seismic information entropy, the time-curves of different second grade blocks in each first grade block are highly similar, but have large difference among second grade blocks in different first grade blocks. Based on statistical physics analysis, this method can reflect the regional tectonic characteristics and overcome the disadvantage of lack of sample size in division of periodicity.

Key words: Weibull distribution, Seismic information entropy, State of earthquake activity, Tectonic characteristics