Recently, some sediment disasters have been occurring every year in various places. The average occurrence for the past 20 years is 500 times a year. It is thought that the sediment disaster caused by a localized torrential rain especially occurs at a weak part on the ground surface, by which an earth and sand movement phenomenon takes place. In this research, artificial satellite data were used to explain the earth flow disaster, which occurred in Miyajima on September 6, 2005. The satellite information data which made use of pre-disaster data showed the usefulness as the risk prediction for weathering slopes of the mountain torrent.