well if you looking for HUGE mud flows, Lahars would be your word. A lahars, are huge mud flows containing boulders and uprooted trees. I'm guessing your going to use this word for a crossword puzzle?
The heavy rains caused a mudflow. The mudflow came down the hill and hit the village.
From what I heard, the electron mudflow traveled about two miles
A mudflow is a mixture of sediment and water that moves down hill in a fluid manner.
A lahar is a specific type of mudflow formed primarily of volcanic material.
Lahar.
Mudflow
magma
After a heavy rain
Mudflow is downslope movement of water that contains large amount of suspended clay and silt.
Mudflow
lahar
http://www.mudflowband.com