In the Andes Mountains of South America, entire towns of thousands of people have been buried suddenly when water and loose materials traveled downhill as a viscous fluid. This type of catastrophic event is known as a

Based on the given description,this type of catastrophic event is known as a:

According to the given question, we are asked to show the name of the catastrophic event which is described from the given scenario about water and loose materials moving downhill.

As a result of this, we can see that the best description for the given scenario is that it is a debris avalanche because it is a type of volcanic condition where soil and water combines and bury large bodies after it has traveled downhill

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Debris avalanche

Explanation:

Debris avalanche is usually caused by unstable volcanic conditions or collapse of a slope and is characterized by the a large amount of soil and sometimes water bodies being buried as a result of the movement of the debris being moved after the collapse.

It is also characterized by water and loose materials traveling downhill as a viscous fluid.