Landslides triggered by Typhoon Morakot with an area over 576m2 were mapped from FORMOSAT-2 images. Recognition and calculation of the number and area of landslides show that at least 22,705 landslides with a total area of 274km2 were recognized in the 7811km2 study area. Among these landslides, 17,417, with a total area of 150km2, are recognized as new ones, and 5288, with a total area of 124km2, are classified as enlarged from pre-existing ones. Out of the 22,705 landslides, there were 22,221 recognized with an area smaller than 10ha; 298 recognized in the range of 10 to 20ha. Twenty-two landslides with an area of over 60ha have also been identified, and the total area of these landslides is 20km2, which is equal to 7.37% of the total landslide area. With respect to exposed rock type, the landslides mainly occurred in Eocene-Miocene slate and Miocene sandstone and shale. In addition, Morakot-induced landslides mainly occurred in areas with cumulative precipitation in the range of 800 to 2600mm, and the magnitude of landslide concentration is roughly linearly proportional to the amount of cumulative rainfall.
All Science Journal Classification (ASJC) codes
- Geotechnical Engineering and Engineering Geology