Answer:
ash and other pyroclastic ejecta become saturated with water
Step-by-step explanation:
Lahars occur more commonly after a landscape has been covered by loose volcanic material, Lahars pick up material as they travel, which can cause damage to structures in their path.
A muddy mass of quickly moving volcanic fragments. Lahars usually contain ash, breccia, and boulders mixed with rainwater, or river or lake water formed by the volcano-related lava flow. The deposit that such a flowing mass produces is known as Lahar.