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How can trapped air contribute to a rapid debris flow?

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landslide This 1995 landslide at La Conchita, a coastal town in California, swept away a hillside road and destroyed a number of houses.

In the context of geology, trapped air acts as a fluidizing agent that can significantly increase the mobility and velocity of certain landslides, specifically rock and debris avalanches.1

When a large volume of rock or debris detaches from a steep slope and falls freely under gravity, the mass can trap a sufficient amount of air beneath or within it. This entrapped air reduces friction and facilitates a very rapid, fluid-like flow of the material. These events, known as rock avalanches or debris avalanches, can reach velocities exceeding 50 meters per second and are capable of traveling long distances, causing extensive destruction. While water is the most common fluidizing agent in landslides, the role of trapped air is a critical factor in the extreme speed observed in these high-volume mass movements.1