STATISTICAL RELATIONS BETWEEN LANDSLIDES INDUCED BY WENCHUAN EARTHQUAKE AND EARTHQUAKE PARAMETERS,GEOLOGICAL AS WELL AS GEOMORPHOLOGICAL FACTORS

This paper is based on investigations of the landslides induced by Wenchuan Earthquake and collection and analysis of the related data. It presents the statistical relations between the earthquakeinduced landslides and other factors including earthquake parameters,geological and geomorphological factors. The results show that: (1)the landslides caused by Wenchuan earthquake mainly occurred in the Ⅶ～Ⅺ intensity districts,there were rather fewer landslides in the Ⅵ and below intensity districts; (2)the earthquakeinduced landslides mainly occurred in the area 300 km from the epicenter,and intensively distributed in the area 200 km from the epicenter; (3)the slopes with the dip angle of 30～50,especially 30～40,are very easy to slide during Wenchuan Earthquake; (4)the earthquakeinduced landslides mainly distributed in the elevation range of 600～1500m,especially 600～1000 m; (5)soft rocks such as mudstone,shale,schist and so on,are the easiest to slide during Wenchuan Earthquake; the combination of soft and hard rocks is secondary to slide; and hard rocks such as granite and carbonate rocks are not easy to slide; only a few old landslides were reactivated by Wenchuan Earthquake.