What term describes landslide movement that occurs predominantly along planar or gently undulating surfaces?

Translational slides refer to a type of landslide movement where the material moves down a slope along a relatively flat or gently undulating surface. This movement typically occurs when the strength of the slope material is exceeded due to factors such as increased water content, reduced cohesion, or changes in load. In translational slides, the materials slide in a cohesive block along the surface, maintaining a defined angle and orientation during movement.

This contrasts with other types of landslide movements that involve different mechanisms. For instance, creep involves a very slow movement of soil or rock downhill due to gravity, typically over long periods, without a clear defined sliding surface. Debris flows are characterized by a mix of water and loose sediment that flows rapidly down a slope, often triggered by heavy rain or rapid melting snow, rather than sliding along a surface. Rotational slides occur along a curved or arcuate slip surface, with the material rotating about a pivot point as it moves. Thus, the distinct feature of translational slides is their movement along relatively planar surfaces, making this term the most accurate description for the landslide movement in question.