Amass movement that involves the sudden movement of a block of material along a flat, inclined surface is called a

slide

Explanation:

A mass movement  or mass wasting can be defined as the movement of large amount of unstable materials lying on an inclined area such as soil, boulders, stones, debris and sediments down the slope typically as continuous or discontinuous mass due to the acting force of gravity. This can be seen in the cases of landslides and mudslides. Slide is a mode of movement and transport of the materials over a flat and inclined surface.

. the sierra madre fault zone of southern california

. the san andreas fault california