Original term: berlahar (Javanese)
Components of a lahar:
(1) water, which may come from melted snow, a crater lake, torrential rains or other source
(2) mud, volcanic ash and debris (rock, trees, plants, etc)
Features of a lahar flow:
(1) large wave of mud and debris coming down the side of the volcano, typically following a valley or riverbed
(2) buries or sweeps away everything that it encounters
(3) hardens into a cement-like solid once it stops
where:
• Roman cement consisted of volcanic ash from Mount Vesuvius (pozzolana) mixed with water, sand and slaked lime.
