1. Geological Survey of Jiangsu Province��Nanjing 210018��China; 2. Key Laboratory of Earth Fissures Geological Disaster��Ministry of Land and ��esources��Nanjing 210018��China; 3. College of Hydrology and Water ��esources��Hohai University��Nanjing 210098��China; 4. China Geokon Instruments Limited Liability Company��Beijing 100080��China 5. Binhu Bureau of Land and ��esource of Wuxi City��Wuxi 214000��Jiangsu��China

In order to study the formation mechanism of Xuelang Mountain landslide��four sensors were suc- cessfully set up�� On the basis of continuous monitoring from January to April��the activity characteristics of rock fis- sures on trailing edge of landslide were obtained�� Monitoring and research shows that consequent slope and mud- stone interlayer are the two major internal factors��while precipitation and low temperature are the two major in- duced factors�� The daily precipitation of 20 mm��the accumulation precipitation 30 ��40 mm in the first two days or 40 ��50 mm in the first three days can be used as the critical early warning index for geological disaster warning and forecasting��