[fractallyte]

I wonder if this is related (in a very large scale sense) to the sand pile model and self organized criticality...

https://en.wikipedia.org/wiki/Self-organized_criticality

The sand pile model: if one builds a pile of sand, dropping onto it a small number of grains at a time, individual grains will slide down the slope - but there's a critical angle at which any additional grains can trigger a catastrophic avalanche.

https://nautil.us/the-math-of-the-amazing-sandpile-238320/

[hinkley]

If one builds a dry pile of sand.

A wet pile of sand has a different angle of repose. Between the lubrication and the rather substantial weight of the water, that's how most mudslides happen.