This is what mud at 60 mph looks like

Source

At least in an animated sense...

This is an animation of the recent Steelhead slide in Washington, based on USGS modelling.  60 mph is actually a 'normal' speed for a landslide or avalanche.  This slide was notable for the release of the volume of soil, as well as additional liquefaction as it hit the Stillaguamish River.

As always, a fascinating, tragic event.