Chi-Chi Earthquake Induced Landslides in Taiwan

Liao [1] pointed out that Chi-Chi earthquake caused about ten thousand landslides to the area, each of which is larger than 625 square meters and that the total area of the landslides exceeds a hundred square kilometers. In their paper on the geotechnical hazard caused by Chi-Chi earthquake, Lin, Liao, and Ueng [2] showed that almost all of the slope failure sites are located to the right of Che-Lung-Pu fault (Fig. 1). However, for those landslides of fault scarp failures, the sliding (or falling) mass moved to the western direction of Che-Lung-Pu fault. Among all the landslides triggered by Chi-Chi earthquake, the most catastrophic and dramatic four will be discussed in greater detail. They are: Tsao-Ling rockslides, Juo-Feng-Err-Shan dip slope failure, stripping of Juo-Juo-Fong (99 peaks), and the Ku-Kuan to Te-Chi section (mileage 34K to 62K) of the Central Cross-Island Highway. Case studies on the Tsao-Ling rockslides and the Juo-Feng-Err-Shan dip slope failure reveal that the chance of reoccurrence is very high for those huge scale landslides. Many highway slopes have been weakened, or even fractured, by the shaking of Chi-Chi earthquake. Rock-falls occurred during subsequent aftershocks and new earthquakes. Debris flows happened from time to times due to heavy rainfalls in February 2000 and April 2000.