This paper describes environmental conditions of Yigong landslide before it occurence and from the 4th to the 41st days during the landslide occurring. With multi temporal different satellite data

through digital image processing and precise registration with the topographic map for the landslide region

the color ortho images are formed. Based on the interpretation of these images

it is understood that the occurrence of Yigong landslide is a large scale gravity erosion activity in the process of Xi\|Ma\|La\|Ya Orogenic movement

and its activity style is “high speed debris flow landslide”. The entire debris flow body has been basically stable since the disaster happened

but the back end of the Zhanalong gully is still moving with the snow avalanche. The exposed area of the landslide has been varied in the limitation of 12.9\

1

1.4 to 12.4\

1

0.0km\+2 and the Yigong lake varied from 19.9 to 43.6 km\+2 during the 4th\

4

1st days since landslide occurred. Owing to snow melting

the lake area became larger and larger quickly but the landslide dam was weak

it was thus deduced that the dam could burst at any time. It was bursted on Jun. 10

that conforms with the deducing result.