the side of the volcanoes and other pyroclastic ejecta become saturated with water
Explanation:
A pyroclastic flows can generate the lahar when they are extreme ty hot and flows with the rocks bedrock. This debris mixes up with the snow met and ice and gets rapidly traveled upwards.
It travels rapidly down steep slopes and a larger can also be formed when a high volume of long duration of rainfall occurs after the eruption. And the volcanic landslides are mixed with water.