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.