The evolution of debris flows since the Wenchuan earthquake in 2008 is documented.
We tracked the landslide-debris movements in the epicentral area from 2008 to 2015.
The rainfall threshold just after the earthquake was one thirds of the pre-earthquake level.
Channelized flows became dominant as more hillslope deposits evolved into channel deposits.
Post-seismic debris flow activities are divided into active, unstable and recession stages.