Sediment Disasters due to the Chi-chi Earthquake in Taiwan, 1999 and Heavy Rainfall after the Earthquake

The Chi-chi earthquake, which occurred on September 21, 1999, generated serious damage mainly in the central Taiwan. The number of deaths and missings caused by the earthquake became the scale which ranks second to the Hsinchu-Taichung earthquake which occurred in 1935. Not only in the urban area but also in the mountainous area, the earthquake caused terrible damage due to the upheaval of the ground, cave-ins and landslides. About two years after the Chi-chi earthquake, two typhoons (Toraji, Nari) crossed over central Taiwan in June and September, respectivelys in 2001. These generated serious damage as well in the same area which had suffered damages from the Chi-chi earthquake. This paper shows the sediment disasters in the mountainous area caused by this earthquake and by these typhoons. The situations of sediment disasters, along with the history of natural disasters in Taiwan, are summarized