Abstract: In the preparing process of large earthquakes and with continuing accumulation of elastic strain energy, the seismic zone may be changed from the original status as a disorder in time and space to an ordered state, and various information associated with the change are likely to increase the degree of order. In this paper, information entropy is introduced to describe the space scanning features of precursor observations. The results show that ① Future anomalous areas are formed near the epicenter before half to 2 months of 4 moderate earthquakes occurred in Fujian region, but there are no relationship between magnitude and sizes of anomalous areas, anomaly, anomalous areas disappeared after the earthquake; ② In the 4 earthquakes, two earthquakes occurred in the abnormal areas of information entropy scanning, although the other two earthquakes occurred in the abnormal area, but the epicenter distance to abnormal central area are less than 100 km.

Key words: Information entropy, Precursory observations, Space scanning