Landslide Interpretation and Magnitude-Frequency Statistics Analysis in The Lushan Basin, Taiwan

The Lushan Hot Spring area in Nantou County, Taiwan, suffered serious sediment disasters after typhoons Sinlaku and Jangmi in 2008, and following Typhoon Morakot in 2009. The basin’s landsldies after the typhoons brought rain was examined using the frequency-area statistics distribution. The critical state indices attributed to landslide frequency-area distribution are discussed and the marginally unstable characteristics of the study area indicated. The landslides were interpreted from Spot 5 images before and after disastrous events. The results of the analysis show that the power-law landslide frequency-area curves in the basin for different rainfall events-induced tend to coincide with a line. The temporal trend of the rainfall-induced landslide frequency-area distribution shows 1/f noise and scale invariance. The landslide frequency-area distribution could be estimated in advance by three-parameter inverse-gamma distribution with a critical slope of 1.0.