**5. Debris flow arising from the earthquake**

Strong earthquakes not only trigger co-seismic landslides but also they affect subsequent rainfall-induced debris flows over a long term because these co-seismic landslides greatly increased the amount of sediment material for potential debris flows (Lin et al.,2006; Tang et al.,2009; Khattak et al.,2010). After the 2008 Wenchuan Earthquake, the earthquake affected areas experienced two rainy seasons till 2010, and a large number of debris ows occurred, which claimed as many as 450 fatalities. It makes the restoration and reconstruction much more difficult (Xie et al.,2008).

In this section, at first, the characteristics of debris flows in the earthquake affected areas are summarized. And then, an approach of simulating debris flow is proposed for disaster mitigation. Finally, a large scale debris flow is simulated so as to show the effectiveness of the proposed.
