Your Daily Volcanology Lesson.

The buzzword around these parts today: Lahar. 

(uccs.edu) Lahar (also called debris flow) is an Indonesian word used by geologists to describe a mudflow or a water-saturated debris flow on a volcano. 

Lahars are powerful forces capable of moving great quantities of debris - house-size boulders, trees, etc. for long distances in a short amount of time. They look and behave like flowing concrete and destroy or incorporate virtually everything in their path. 

Photo: Reuters via Yahoo News